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jklinstein
Gunboards Member



USA
20 Posts
Posted - 08/23/2006 : 10:32:43 AM
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When I first got my CETME it ran flawlessly, but reading about ground bolts made me stop until I could inspect it. My bolt length is about 1.820" and the rear surface appears as though it may have been ground & polished (but it still has rounded edges). Comparing that to the information in the table of bolt length data in another thread, I came to the conclusion that my bolt is approximately .015" too short so I ordered larger rollers to "fix" my ground bolt.

But when inspecting the locking piece I found that the angled surfaces which push on the rollers also appears to be uniformly polished, not matching the rest of the locking piece. Is this normal, or did someone alter this locking piece too?

If I had a digital camera I'd have included the pictures. Does anyone have a good picture of a "normal" locking piece, especially of the surfaces which push out the rollers?

Help,
Jacob

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Edited by - jklinstein on 08/29/2006 2:38:20 PM

blue gascon
Gunboards Super Premium Member



USA
324 Posts
Posted - 08/23/2006 : 8:55:05 PM
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Actually, that's normal. The ramp surfaces of the locking piece that the rollers move along are ground and polished to set the final angle. They do look different from the rest of the surface of the locking piece. The wear to watch for on the locking piece is indents on the ramp surfaces where the rollers rest at bolt lockup. It's normal to see a bit of a mark where the rollers rest, but deeper indents can be a headspace problem.

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Contendo ergo sum- (I shoot, therfore I am)- COG #26

"Democracy is two wolves and a lamb voting on what to have for lunch. Liberty is a well-armed lamb contesting the vote!"
Benjamin Franklin


highestangel
Gunboards.Com Gold Star Member



USA
1504 Posts
Posted - 08/27/2006 : 7:55:19 PM
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Jklinstein, Adding +4 rollers will only mask the problem, and give a false reading on the bolt gap measurement(because of the shorter bolt length). Get a correct length unground bolt(around 1.835"), new, or, slightly used locking piece, and probably +4 rollers, and then measure your bolt gap, to get a more accurate reading on the bolt gap. The bg reading will probably be less than with a ground bolt, and +4 rollers, but at least it'll be an accurate reading of the TRUE bolt gap. I'm by no means an expert on this, but,... I did stay at a Holiday Inn, last night.
Michael


jklinstein
Gunboards Member



USA
20 Posts
Posted - 08/27/2006 : 8:48:26 PM
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A new bolt group, with +4 rollers, and less than 0.003" bolt gap. I don't have the equipment to fix it, and don't know how to find a gunsmith that knows how the roller delayed blowback systems work.


highestangel
Gunboards.Com Gold Star Member



USA
1504 Posts
Posted - 08/27/2006 : 9:32:27 PM
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"A new bolt group",... Did you mic the length of both your old, and new bolts? Did you also mic the old, and new rollers to get a comparison? I've also seen the wrong locking pieces sent, or, more used parts, than the original pieces. Check all of these measurements, and try different combinations of old parts, and new parts, and record the bolt gap measurements of the various combinations. Last, but, not least, you are charging the rifle, and DRY(empty chamber)firing it, before taking the bolt gap reading. I'm sure you are, but, just checking everything, as some people have done this incorrectly before.
Michael


jklinstein
Gunboards Member



USA
20 Posts
Posted - 08/28/2006 : 11:22:55 AM
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quote:
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Originally posted by highestangel

"A new bolt group",... Did you mic the length of both your old, and new bolts? Did you also mic the old, and new rollers to get a comparison? I've also seen the wrong locking pieces sent, or, more used parts, than the original pieces. Check all of these measurements, and try different combinations of old parts, and new parts, and record the bolt gap measurements of the various combinations. Last, but, not least, you are charging the rifle, and DRY(empty chamber)firing it, before taking the bolt gap reading. I'm sure you are, but, just checking everything, as some people have done this incorrectly before.
Michael

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Michael,
The old bolt head length is 1.820", the new one is 1.835. The rollers also checked out (old = .315"[8.00mm], new = .3165"[8.04mm]) The new set is obviously unissued. I'm charging on an empty chamber with the barrel pointed down at a 45 degree angle, and I've measured both dry-fired and unfired.

I also put the +4 rollers in the ground bolt (original assembly) and it did not change the bolt gap. I think it might be resting on the locking piece (i.e. locking piece resting on the bolt head). This rifle seemed to be 100% reliable with no problems for a few hundred rounds, then I heard about the CIA ground bolt issue. The only thing I have not tried is the new bolt with the original bolt group.

I don't think it would be right to sell this to someone who wasn't going to have it fixed, but I don't know who I can get to fix it (locally).


jklinstein
Gunboards Member



USA
20 Posts
Posted - 08/29/2006 : 08:33:05 AM
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I was wrong about one thing... I checked my notes and I had not put the +4 rollers in the ground bolt. With 8mm rollers and the ground bolt I had .006" gap. With +4 rollers it increased to around .008". Adding the new locking piece (to the ground bolt - which is .015" short - with +4 rollers) brings my gap to .017 (.018 if I'm willing to push the gauge with some force). As I see it I'm technically still out of spec with a "real" gap of .002-.003.
I tried the new bolt with the original bolt group, and couldn't fit the .003" feeler in the gap.

I inspected the face where the bore & trunnion should be flush, and the barrel is slightly recessed. The shape of the bolt is just visible on the face of the trunion. The original locking piece also shows signs of contact with the bolt around the face of the firing pin "cone".

By increasing the bolt gap from an "artifical" 0.006" to 0.017" have I accomplished anything?

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Edited by - jklinstein on 08/29/2006 2:43:10 PM


jfowl31
Gunboards.Com Silver Star Member



USA
713 Posts
Posted - 08/29/2006 : 8:42:48 PM
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one weird thing i did to increase my bolt gap was cleaning the face of the chamber where the bolt slams up against really good. it had a nice carbon build up that had been missed by me in my cleanings, this little task raised my gap another few thousandths. Have youfired it with the new stuff installed? maybe it needs to "break in" so to speak. and you have a new Locking piece?

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COA #106121 COG #1000 NRA #148440199

Copenhagen is my anti-drug!



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Edited by - jfowl31 on 08/02/2007 09:38:14 AM


Drakejake
Gunboards Member



89 Posts
Posted - 10/11/2006 : 5:49:44 PM
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I spoke to a Century gunsmith yesterday. He told me that their standard for minimum bolt head length was 1.825. My ground bolt measures 1.816. The smith told me that I could have a case separation and that I should send my rifle to Century for examination. My fired cases show no sign of trouble. I have ordered a new bolt assembly but I am concerned that my rifle will not function with a full-length bolt.

Drakejake

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Edited by - Drakejake on 10/11/2006 5:51:07 PM


Bud
Gunboards.Com Gold Star Member



USA
2680 Posts
Posted - 10/11/2006 : 6:33:22 PM
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quote:
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Originally posted by Drakejake

I spoke to a Century gunsmith yesterday. He told me that their standard for minimum bolt head length was 1.825. My ground bolt measures 1.816. The smith told me that I could have a case separation and that I should send my rifle to Century for examination. My fired cases show no sign of trouble. I have ordered a new bolt assembly but I am concerned that my rifle will not function with a full-length bolt.

Drakejake

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Due to liability, century ends up keeping your rifle and destroys it and offers you wholesale price for it, like $250 bucks, from what I read, best not send it back for nothing. Besides, even when they did fix things years ago on these, the rifles would come back looking like it was shoved into a grinder all over the place, with the help of a large pair of rough channel locks, which is great if you are looking for that "been dragged trough the 1980's Iran/Iraq War" kind of look, only thing missing would be a burst of ak47 bullet holes along the receiver for a more authentic look.


Drakejake
Gunboards Member



89 Posts
Posted - 10/11/2006 : 6:50:05 PM
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Bud,

I share your concerns about sending the rifle back. My view is that I have a good rifle that works fine. Century tells me there are safety issues (caused by their own actions) and I cannot ignore that. But I would rather replace some parts myself rather than give them a second chance to sabotage this rifle.

Drakejake


myco4you
Gunboards Member



44 Posts
Posted - 10/13/2006 : 11:23:13 PM
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If your new bolthead and rollers have decreased the gap to 0 and the charging handle has normal play when dryfired,your barrel will have to be moved and repinned!


Drakejake
Gunboards Member



89 Posts
Posted - 10/14/2006 : 09:45:58 AM
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I understand I can use a new locking piece and bigger rollers to increase headspace. I hope to have my new parts set on Monday. I am not going to have the barrel repressed. I will sell the rifle before doing that. If I determine that headspace is actually OK despite the ground bolt, I may continue shooting the rifle. If, for example, I replace the bolt head and the rifle will not go into battery with a round in the chamber, that will suggest that the original headspace was OK and I was worried about nothing. I have just bought a Cetme with stainless receiver on Gunbroker.com. Because of a planned trip, I will probably not get that rifle until the end of the month.

Drakejake

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Edited by - Drakejake on 10/14/2006 09:51:59 AM


arnaiz
Gunboards.Com Silver Star Member



730 Posts
Posted - 10/14/2006 : 3:27:33 PM
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DO NOT FIRE any Cetme with groung bolt.
Its just a simply way to make up rifle specs meassurements, but rifle will be out of specs.


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Saludos Jorge


Drakejake
Gunboards Member



89 Posts
Posted - 11/15/2006 : 9:03:52 PM
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I have just replaced the rollers and locking pieces on my two recently purchased Cetmes. The second one had an unground bolt but no bolt gap. Now the gap is is about .014. The first Cetme had a ground bolt (c. 1.816) and a gap of .010. Even with plus four rollers and a new locking piece, an unground bolt in this rifle produced no bolt gap. So I have decided to be happy with a ground bolt, a gap of .014, and new rollers and LP. I am not convinced that a ground bolt is a problem if worn parts have been replaced, there is a proper bolt gap, the rifle functions well, and fired cases show no signs of primer or case bulge. More I will not do to this rifle (has stamped receiver with modest dimpling), although I may decide to sell it but keep the one which has a stainless receiver and HK retractable stock transferred from the other rifle.

Drakejake


cma g21
Gunboards Member



USA
13 Posts
Posted - 11/16/2006 : 5:26:24 PM
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Drakejake,

You state, "I am not convinced that a ground bolt is a problem if worn parts have been replaced, there is a proper bolt gap, the rifle functions well, and fired cases show no signs of primer or case bulge.."

If I understand correctly, your CETME with the ground bolt now has a true bolt gap of -.008 (.014 - (1.835-1.816)). Wouldn't that be .012 below minimum spec?

Also, couldn't one of the worn parts (in need of replacing) be the ground bolt?


edited for math error

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Edited by - cma g21 on 11/16/2006 6:19:13 PM


Drakejake
Gunboards Member



89 Posts
Posted - 11/16/2006 : 5:48:25 PM
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CMA,

Right now I do not accept the idea that a ground bolt gives a completely false reading of bolt gap or has to be compensated for. For interaction between the bolt head, bolt carrier, and locking piece, I believe a bolt gap is a bolt gap PERIOD. If you have a bolt gap of .015 with a ground bolt, that gap is still real and serves the purpose of allowing the locking piece to move fully forward to completely lock the rollers in place in the trunnion. It is true that with a ground bolt the bolt gap no longer is a good measure of part wear. There are those that believe that bolt gap serves that purpose only with a precision built, original factory rifle, not with the inferior products of Century Arms. At any rate, I replaced the locking piece and rollers (with plus fours). I cannot replace the trunnion or repress the barrel. So I have a rifle that worked when I got it, has some new parts, has a proper bolt gap, and still works. I have read hundreds of comments on these issues on the Internet and I have thus far not found any real proof that using a ground bolt is a safety hazard. I think some of the manuals being used contain incorrect or misleading statements and are being used as a basis for unwarrented assumptions. But I am open to new information and continue to research these issues. (Century has stated that grinding a bolt is an acceptable way to get proper bolt gap, but this statement does not seem to have been verified or refuted. http://www.gunsnet.net/forums/showthread.php?t=110291)

Drakejake


Drakejake
Gunboards Member



89 Posts
Posted - 11/16/2006 : 6:26:39 PM
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I think people should admit that the Century Cetmes/G3 Sporters are a strange case, for the following reasons:

When you buy a rifle, inspect it, clean it, and shoot it, and it works well, usually that is enough. But not with the Cetme.

You also have to check bolt gap. But even if this checks out, this is not enough.

You also have to check for worn parts and replace them, but this is not enough.

You also have to check the bolt head for grinding. If the bolt head is ground and you cannot get good bolt gap with an unground bolt, you have to trash the rifle or reconstruct it at a cost that approaches the original purchase price.

And you must do all this because of conflicting statements posted on the Internet by people you don't know.

Very strange!

Drakejake


jfowl31
Gunboards.Com Silver Star Member



USA
713 Posts
Posted - 11/17/2006 : 01:36:15 AM
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its not just the cetme... also the HK's.

the reasoning for it is because the rifles will still work perfectly most of the time when parts are worn, unlike many other rifle designs.

the problem with a ground bolt which makes it an unacceptable method is that they only grind the spot whre bolt gap is measured, so it gives a truly "false" reading. the bolt gap is still too small the rest of the way around the bolt except for where you put that feeler guage in to fool you into thinking there is a gap there. the gap is just as you said there to allow the LP to lock everything..........

but if they ground the bolt and did not shorten the ENTIRE bolt, there still is no gap or a gap too small, and it is STILL unsafe. you can do whatever you want, because its a free country, but with a gap of .012 under CETME spec, the rifle is not considered safe by them. but its your rifle and your "spec" is apparently all that matters to you...

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COA #106121 COG #1000 NRA #148440199

Copenhagen is my anti-drug!




Drakejake
Gunboards Member



89 Posts
Posted - 11/17/2006 : 08:34:39 AM
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JFOWL31,

I do not really understand your comments but what I am looking for is some authoritative, verifiable statement that firing the Cetme with a ground bolt is dangerous. Without having such proof, I do not think it is reasonable to trash the rifle or have it reconstructed. Up to now, I have not seen such evidence. I am sure that hundreds or even thousands of people have Cetmes with ground bolts, do not know this, would not care if they did know, have well-functioning rifles, and will never have a case separation or explosion. If these rifles were unsafe, there would be many, many messages reporting explosions. And Century arms would have been sued repeatedly for selling unsafe rifles. But I have never read about any such lawsuits. The few reports of case separations or explosions refer to the use of commercial .308, excessively hot handloads, or barrel obstructions. Please point out one definite example of a case separation or explosion caused by a ground bolt in a rifle with new rollers and locking piece and in spec bolt gap. Because of all the contradictory statements made about bolt gap and headspace on the Internet, I am sure that there is quite a bit of confusion and misunderstanding. For example, many people have stated that bolt gap is the same as headspace or that you can check or set headspace by checking or changing bolt gap, but HK experts have said this is incorrect.

Thanks,

Drakejake


Meinander
Gunboards Premium Member



239 Posts
Posted - 11/17/2006 : 2:17:17 PM
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If the bolt has to be ground down to make a gap, then the locking piece (LP) is too far forward. The LP engagement with the rollers is triangle shaped and moving the LP forward moves the rollers outward, right? My thought is that there is a finite range the LP can move forward and push the rollers outward and lockup still be acceptable.


jfowl31
Gunboards.Com Silver Star Member



USA
713 Posts
Posted - 11/17/2006 : 2:49:46 PM
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quote:
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Originally posted by Drakejake

JFOWL31,

I do not really understand your comments but what I am looking for is some authoritative, verifiable statement that firing the Cetme with a ground bolt is dangerous. Without having such proof, I do not think it is reasonable to trash the rifle or have it reconstructed. Up to now, I have not seen such evidence. I am sure that hundreds or even thousands of people have Cetmes with ground bolts, do not know this, would not care if they did know, have well-functioning rifles, and will never have a case separation or explosion. If these rifles were unsafe, there would be many, many messages reporting explosions. And Century arms would have been sued repeatedly for selling unsafe rifles. But I have never read about any such lawsuits. The few reports of case separations or explosions refer to the use of commercial .308, excessively hot handloads, or barrel obstructions. Please point out one definite example of a case separation or explosion caused by a ground bolt in a rifle with new rollers and locking piece and in spec bolt gap. Because of all the contradictory statements made about bolt gap and headspace on the Internet, I am sure that there is quite a bit of confusion and misunderstanding. For example, many people have stated that bolt gap is the same as headspace or that you can check or set headspace by checking or changing bolt gap, but HK experts have said this is incorrect.

Thanks,

Drakejake

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how about the fact that if you call century and send in your rifle, telling them that they installed a ground bolt in your rifle and threaten a lawsuit, they fix it immediately no questions asked?

sounds to me the know they did something wrong.

also, did they grind the entire bolt face or only the part where you stick the feeler guage in. ALL of the ground bolt pictures ive seen and ground bolts ive examined were only ground where the feeler guages were stuck in to check the BG. SO obviously, the rest of the way around the bolt the gap is not present. unfortunately, they dont make feeler guages to measure at the back of the bolt, so one has to measure and do some very simple math to calculate the BG. its not real hard. once the true BG is calculated, YES there are tons of documents (published) that state the rifle is safe/not safe depending on where your BG falls. they are called owners manuals. if it were safe to shoot a rifle that is out of spec, why are the parts made to correct the problems?

once again, its a free country, and its your rifle and your face.

ive driven cars that by some (including the factory) could have been considered unsafe, so i understand your logic, but its a whole damn lot cheaper to fix a rifle than buy a new car.

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COA #106121 COG #1000 NRA #148440199

Copenhagen is my anti-drug!




jklinstein
Gunboards Member



USA
20 Posts
Posted - 11/17/2006 : 3:08:09 PM
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Maybe a good "gut check" on this is, "Would you use this rifle with a group of Boy Scouts?"


Drakejake
Gunboards Member



89 Posts
Posted - 11/17/2006 : 3:23:19 PM
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Shortly after getting the rifle, I contacted Century and told them about the ground bolt. The gunsmith told me I might have case separations and that I should send the rifle in to them. He implied that my bolt head, at 1.816, was below their minimum length of, say, 1.820 or 1.825. They would not send me any replacement parts. To avoid legal liability, Century probably tells every caller to send the rifle in. I decided not to send the rifle to them for the following reasons:

In some cases Century has kept the rifle and given a $200 credit.

In some cases Century has refused to repair if any parts have been replaced (the warranty has been voided).

I have read that Century in the past has stated that a ground bolt is not a safety problem, that grinding the bolt is an acceptable way to get proper bolt gap, and that they will not do anything about such bolts.# (see below)

If you do not trust Century to sell a safe rifle, how can you expect them to do a good, safe repair?

My rifle functions well now, so I could be worse off once Century works it over.

I was willing to buy the parts and replace them myself.
______________________

I would not drive a car or fire a gun I believed to be unsafe. I do not believe my Cetme to be unsafe. I have seen no proof that it is unsafe. I do not believe Century would still be in business if dozens of their rifles had exploded due to poor assembly or excessively worn parts. The problems with Century Cetmes have related to functioning, not to safety, so far as I know. I am aware that some people have asserted that a ground bolt must be replaced but I do not know those people, do not know their qualifications, and do not know the basis for their statements. I have read a great deal about the roller delayed action and have not found anything that tells me the rifle is unsafe to fire. But I am open to new information.

The rear of my bolt head was ground all over and very professionally. I checked it with a digital caliper. You can read on the Net Century's statement on exactly how they grind the bolts.

# 2003 statement from Century:

"Hi. Here's exactly how we do this:

The Spanish Ministry of the Army Maintenance Manual dated June 3, 1975 authorizes two methods of adjusting the headspace on the CETME rifle. One is to change the rollers on the bolt head and the other is to install a smaller bolt head. To repair or shorten the bolt head the manual lists the required tools as a ceramic file and a hand grinder. To ensure a uniform square surface and maintain closer tolerances, Century uses a Brown & Sharpe No. 2 surface grinder with an auto feed. To ensure that a false reading is not registered, each rifle is head spaced twice. The first time without the cocking handle in the rifle and the second time with the cocking handle installed. Century measures and maintains head space in accordance with the Spanish Ministry of the Army Maintenance Manual at .004 - .014 of an inch.

We do not accept returns on these rifles for bolt head replacement, as for the above listed reasons there is not a safety issue regarding head spacing.

Thank You, CIA" (quoted on the Guns Network LLC)



Thanks,

Drakejake


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Edited by - Drakejake on 11/17/2006 7:07:54 PM


jfowl31
Gunboards.Com Silver Star Member



USA
713 Posts
Posted - 11/18/2006 : 02:26:08 AM
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http://www.cetmerifles.com/forum/vb/showthread.php?t=15515

this thread here tells me that with enough pushing, century truly does know that they are unsafe... otherwise they wouldnt be fixing them. why would they admit defeat and fix the rifles of those who were persistant enough. really all it comes down to is calling century and sending in your rifle. it comes back with a new bolt head all that, and in spec.

but again, who needs documented information other than the manuals?

century is the ONLY ones who claim that they were told grinding the bolts was ok. id want to see some paperwork on that. theres countless published things that say every way to fix the gap except grinding the bolt... and if century does in fact replace ground bolts, seems obvious to me.

but once again, it aint my rifle, and i know mines in spec with new parts...

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COA #106121 COG #1000 NRA #148440199

Copenhagen is my anti-drug!




Drakejake
Gunboards Member



89 Posts
Posted - 11/18/2006 : 10:21:36 AM
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CIMMARONKID's rifle had many more problems than mine. In his thread you find the statement by Century that they wouldn't do a repair to a rifle because if was two years' old and out of warranty. My rifle is more than two years old. Have you read of Century repressing a barrel to get a bigger bolt gap? Unless they do this, I have done everything to my rifle that they can do: put in new locking piece and plus four rollers.

Yes, Century does repairs and even replaces rifles, but I do not think the odds favor their helping me in this case. At any rate, I do not think there is anything wrong with my rifle at this point.

Thanks for the comments,

Drakejake


jfowl31
Gunboards.Com Silver Star Member



USA
713 Posts
Posted - 11/18/2006 : 2:53:24 PM
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im pretty sure everybody realizes that you think theres nothing wrong with your rifle.

simple answer is... there is.

go to ANY HK or Cetme forum out there and ask you question and everyone will tell you that she aint safe.

And if memory serves me correctly (sometimes it doesnt) you said you were still shooting the rifle with a ground bolt installed. install a new bolt, and go from there. no need to repress the barrel just yet.

cimmaronkids rifle did have many more individual problems than yours, i dont get the point. his rifle was well out of warranty, and with one simple letter, century jumped all over it and fixed EVERYTHING. If you go off on em and tell them all youve been through, and tell them the barrel needs to be repressed in order for it to be a safe rifle, and possibly threaten a letter to the BBB, or your lawyers, youll get it fixed for free.

and Century will eventually admit that your rifle is indeed unsafe, after you show them that you know a little bit about them. if the rifles werent unsafe with ground bolts, and century actually did get permission to grind them, they wouldnt be replacing them for the people who try hard enough. case and point.

they got a bad rap by producing so many UNSAFE rifles by grinding the bolts, and they are now infamous for this horrible deed with every cetme and Hk collector out there. if thousands and thousands of people KNOW its wrong, and all the manuals say its wrong and ONLY the company who fudged it all up in the beginning says its OK, and then even they fix rifles made this way... what MORE proof do you need that its unsafe. I hope that goes through your head when you teach your little son or grandson to shoot with that rifle. it may run perfectly now... it may run perfectly for the next 5000 rounds, but good ole number 5001 could be a kaboom. just get it fixed or sell it and go for one thats not a lemon.

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COA #106121 COG #1000 NRA #148440199

Copenhagen is my anti-drug!




Drakejake
Gunboards Member



89 Posts
Posted - 11/18/2006 : 4:19:29 PM
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It is clear to me that you have have no facts to back up your statement that firing a Cetme with a ground bolt head is unsafe. And it is also clear that I am not going to change my mind based on someone's unsupported assertions. So I guess we must be content to disagree and let others make their own judgments on these matters.

Drakejake

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Edited by - Drakejake on 11/18/2006 4:20:53 PM


myco4you
Gunboards Member



44 Posts
Posted - 11/18/2006 : 6:00:41 PM
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It is a well established fact that Century decided to re-engineer the rifle by grinding the bolthead,due to their error in assembly.The barrel is not pressed to the right dimension,so rather then correct it with a lot of labor involved,they decided to shorten the bolthead by grinding.This will make the rifle appear to have an acceptable gap.
You have already stumbled upon this defect when you installed a correct bolthead,and found that your gap has been reduced to 0.
The armory would take the rifle out of service if the bolthead gap fell below listed tolerance after new pieces were installed.They would never grind the bolthead.
Read the information at cetmerifles,or any of the HK sites,and decide for yourself.If after you have done your research,and still insist your rifle is fine,then nothing else can be said on this matter.
Your attitude reminds me of a saying my old boss used to say-"You can lead a horse to water,but you can't make him drink"


jklinstein
Gunboards Member



USA
20 Posts
Posted - 11/18/2006 : 8:05:12 PM
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Drakejake,

With a ground bolt your locking piece can come to rest AGAINST THE BOLT HEAD instead of being supported by the rollers. But if you're really convinced that firing an UNLOCKED 7.62x51 rifle is no problem, please buy mine at http://itemsforsalenow.blogspot.com/

jklinstein

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Edited by - jklinstein on 11/18/2006 8:09:21 PM


Drakejake
Gunboards Member



89 Posts
Posted - 11/18/2006 : 8:06:09 PM
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I have already read everything on the Internet relating to this subject. I am a professional researcher (26 years experience) and have spent many hours doing searches and reading posted messages on Cetme ground bolts, bolt gap, and headspace. I have read the most important messages several times. Do you have any facts or specific references relating to whether it is safe to fire a Cetme with a ground bolt?

Thanks,

Drakejake

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Edited by - Drakejake on 11/18/2006 8:09:03 PM


jklinstein
Gunboards Member



USA
20 Posts
Posted - 11/18/2006 : 8:13:53 PM
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Drakejake,

I'm a degreed mechanical engineer with over 10 years of experience designing crap so it won't fall apart or kill someone. If I wanted to light a slow fuse to a bomb and hide it in a rifle, I'd grind the bolt on a CETME and give it to a shooter who didn't understand the mechanics involved.



jklinstein
Gunboards Member



USA
20 Posts
Posted - 11/18/2006 : 8:15:12 PM
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Drakejake,

Even if it were possible to "read everything written" on any subject, that does not necessarily imply understanding.


jfowl31
Gunboards.Com Silver Star Member



USA
713 Posts
Posted - 11/19/2006 : 02:38:42 AM
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quote:
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Originally posted by myco4you

It is a well established fact that Century decided to re-engineer the rifle by grinding the bolthead,due to their error in assembly.The barrel is not pressed to the right dimension,so rather then correct it with a lot of labor involved,they decided to shorten the bolthead by grinding.This will make the rifle appear to have an acceptable gap.
You have already stumbled upon this defect when you installed a correct bolthead,and found that your gap has been reduced to 0.
The armory would take the rifle out of service if the bolthead gap fell below listed tolerance after new pieces were installed.They would never grind the bolthead.
Read the information at cetmerifles,or any of the HK sites,and decide for yourself.If after you have done your research,and still insist your rifle is fine,then nothing else can be said on this matter.
Your attitude reminds me of a saying my old boss used to say-"You can lead a horse to water,but you can't make him drink"

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my understanding, and someone may correct me if im wrong, is that century never removed the barrel from the trunnion when they got the parts kits. so they never actually screwed up with the barrel pressing, the kits were just worn out. butthey still corrected the problem incorrectly.

and drakejake, it IS obvious to me that we wont agree on this one, which i think is sad. thats why ive ended (almost) all my posts with.. its your rifle...

i dont even have a dog in the fight so to speak as my rifle had an in spec BG and funtioned perfectly out of the box with all new parts, but i made my purchase after reading a lot of info out here and made sure i didnt get a lemon.

so it seems to me that since you are such a professional researcher and have done that for so long, you would have researched this rifle before you just bought it and maybe you could have bought one that wasnt butchered by the good ole monkeys.

but since you want facts, how about the fact that century is fixing the rifles and installing new bolts and getting gap from them after putting new bolts in? you never told me your rebuttal to the fact that century has admitted their mistake by fixing broke rifles.

ill wait patiently while you explain to me why a company like century is taking the man hours of their "top techs" to fix "perfectly safe" rifles (in your opinion).

do you just think everyone is out to get you, or are you trying to fool yourself into thinking its safe because it might take some work to get it right?

oh well...

jklinstein, im glad your taking the high road, realizing the problems with your rifle and thus selling it at a discounted price. id venture to guess that if you tucked it away in the back of the safe, youd make quite a good bit of money waiting a few years to sell it when the prices go up some more... especially if more gun control laws take pplace and possibly another AWB. i dont like to get paranoid and speculate, but the rifle wont lose value in keeping it, and its likely to gain a lot very soon.

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COA #106121 COG #1000 NRA #148440199

Copenhagen is my anti-drug!




jfowl31
Gunboards.Com Silver Star Member



USA
713 Posts
Posted - 11/19/2006 : 02:45:02 AM
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jklinstein... whats your gap at again with the +4's and new bolt and locking piece? and where did you buy that locking piece, and was in fact new? maybe it wasnt really new, maybe you should try a new one just in case it may raise things even more. i dunno, jsut more speculation, but with all the work youve put into the rifle, itd be nice to see it stay in your hands. they sure are fun rifles.

SOME sources Ive read said that the BG could be as low at .002 so your rifle may be on the VERY low end of safe.

I also saw a long while ago, and i cant seem to locate them now, some +6 rollers and even +8's.

this would certainly raise you into spec. ill look around through my favorites and saved pages and see if i can dig them up.

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COA #106121 COG #1000 NRA #148440199

Copenhagen is my anti-drug!



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Edited by - jfowl31 on 11/19/2006 02:51:42 AM


Drakejake
Gunboards Member



89 Posts
Posted - 11/19/2006 : 09:05:31 AM
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As recently mentioned, some posters state that Century does not reset barrels (I don't know about this one way or the other) in trunnions but merely takes the two as they come from the old rifle and welds them into the new receiver. This means that the renovated rifle has the same headspace as the original. Headspace in these rifles is determined by the relationship between the barrel and the trunnion.

Why is there no bolt gap with an unground bolt head in some Century rifles? Because the recesses for the rollers in the trunnion are so worn that the locking piece goes further than spec to achieve lock-up. By grinding (shortening) the bolt heads, Century allows the locking piece to go far enough into the bolt head to compensate for the worn trunnion. Since headspace is OK and full lockup is being achieved, what is the danger?

(I am returning to the key issue rather than going back over all of the prior arguments, sidepoints, personal attacks, diversions, etc., in prior messages.)

Drakejake

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Edited by - Drakejake on 11/19/2006 10:49:35 AM


myco4you
Gunboards Member



44 Posts
Posted - 11/19/2006 : 3:38:30 PM
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Let me clarify my previous post.When the technicians at Century made the rifles,they welded the trunion with barrel to the new receiver.The finished product was not correct.Rather than press the barrel to reset to proper specs,they reengineered the rifle by grinding the bolthead.
With a ground bolthead,you will appear to have a gap,but the timing of the delay has been altered from HK design.The delay is what holds all the pressure from firing before the bolt unlocks.The rollers are the only mechanical means of holding the bolt closed.If the timing is altered,the bolt will unlock differently than designed.
This is my limited understanding of a delayed-blowback rifle operation.I am sure that other,more informed individuals can give more detailed explanations as to design and problems with Century modified CETME rifles.Try cetmerifles.This subject has been discussed so many times.I do not recommend you enter with your continued attitude that your rifle is fine,as you will be open to attack by many posters.
Nobody wants to be holding a rifle that can unlock when it's not supposed to.Why take the risk when an easy solution has already been accepted.Have the barrel pressed to proper specs,then your new,unground bolthead will show proper gap,and your timing delay will be as designed by factory engineers,not Century techs!



jfowl31
Gunboards.Com Silver Star Member



USA
713 Posts
Posted - 11/19/2006 : 11:16:58 PM
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how i see it is this... basically the same as myco4you. by grinding the bolthead, the timing is completely off, and really truly there is no reason to have specs for the bolt gap unless all bolts are the same length. by shortening the bolt head to get a "in spec" gap, you are making it so that the rollers push out way too wide. they would do this regardless, but thats why you measure it and get feedback. the rollers push too far out, thus riding too high on the Locking Piece, and thus screwing up the timing of how the system was designed to work.

the bolt gap is not where the safety issue occurs. the bolt gap is simply a measurement to tell you how far up the Lp the rollers are. thats where the safety issue is. its not the fact that the bolt and carrier are touching or too close together, they are just an indication of the position of the rollers, and when you shorten the bolt to give a gap, you are masking the fact that the rollers are pushed too far out and are sitting too high on the LP. basically century didnt understand the way the rifles worked, and just knew that the bolt gap was supposed to be a certain number... they didnt understand why the BG was supposed to be that number. so they ground the bolts to get a desired "number" but changed nothing about why the rifle was unsafe to begin with.

so since you think everyone is personally attacking you, i hope that explains why everyone is not just a little upset at the fact that you are trying to convince yourself you have a safe rifle despite what logic, and HK/cetme designers/engineers/gunsmiths tell you.

hope that helped... maybe it wont change anything in your mind, but hopefully it will keep others who may not be as informed and are just here reading from making the same mistake.

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COA #106121 COG #1000 NRA #148440199

Copenhagen is my anti-drug!




Drakejake
Gunboards Member



89 Posts
Posted - 11/20/2006 : 12:30:56 AM
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You guys just can't come up with any proof, can you? You are committed to some oversimplified ideas you picked up somewhere and refuse to do any new or independent thinking. And your delicate feelings are hurt if someone doesn't buy your act. By the way, who made you guys experts? Please, let me see your credentials. I was warned about the gay Nazi HK thing.

Ha, ha, ha--just joking!!!

Drakejake


jfowl31
Gunboards.Com Silver Star Member



USA
713 Posts
Posted - 11/20/2006 : 02:30:46 AM
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dude wheres your proof? dont be an ass because nobody agrees with you. and the fact that nobody agrees with you trying to convince yourself of something that MANY experts including just about EVERY HK gunsmith in the nation have said is bad makes you look like an idiot. i dont know how i can be more frank than that. Cetmes got a bad name back in the day because of the fact that century did a bad job building these rifles, but mostly because they ground the bolts. I say just about every HK gunsmith in the nation because there may be one somewhere that agrees with you, but he hasnt spoken up anywhere yet, so i wont make that statement.

The deal is, WE dont need proof. The proof is in the facts. You have tried to give your "proof", but the company you got your proof from has gone back on that statement and is now fixing those "perfectly fine" functioning rifles. in other words, they admitted their lie/mistake. it could have been ignorance on their part or they could have been trying to sneak it by the consumer... either way, they have changed their stance.

Its not about new or independent thinking... thats assinine. is it new or independent thinking to consistently shoot double loaded rounds or grossly overloaded rounds? everyone says its wrong, so i guess that makes it independent... so it must be right. theres no logic in your thinking.

its VERY obvious to most here that you are trying to convince yourself that your rifle is fine because you either dont have the time or the means to fix it. Get over your pride and open your eyes. Just because not everything you read on the internet is true, doesnt mean nothing on the internet is true... and besides all that, the manuals and such made for these rifles tell a person how to check bolt gap, and how to fix them. CENTURY is the ONLY place to say that a bolt can be ground because they are the only ones to grind them, and now they dont even stand behind what they say. and besides all that, your bolt as you stated earlier is even BELOW century's standards as its shorter than even THEY said it could be. so even if you like their old way of thinking, youre still not safe according to the ones who you get your proof from.

take the plank outta your eye and wake up.

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COA #106121 COG #1000 NRA #148440199

Copenhagen is my anti-drug!




jfowl31
Gunboards.Com Silver Star Member



USA
713 Posts
Posted - 11/20/2006 : 02:59:13 AM
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now im done being an ass in return to you being an ass. maybe we can get along and figure this thing out.

just explain to me this... really no sarcasm in this post.

why exactly is bolt gap needed, what purpose does it serve?

heres my answer, along with Hk gunsmiths in Austin, and every other "expert" i've read material from:

bolt gap is an indication of how far the rollers are along the LP... aka what "stage" the rifle is in. if a gap is too small it indicates that the rollers need to be larger so that they sit further "down" (towards the small end) the LP. if the BG is too high, it indicates that the rollers need to be smaller and be further "up" the LP. if the gap cant be put in spec with different sized rollers, a new LP or bolt head are in order. if this doesnt fix it, the barrel mux tbe repressed to the right distance away from the indents in the trunnion.

The reason a bolt can't be ground is because once that bolt is ground, it gives a false reading of where the rollers are along the LP. lets say you have a new bolt, lp, and +0 rollers installed and your gap is .001. if you grind your bolt, the gap DOES get bigger, but the rollers are still in the same stage along the LP. basically, you accomplished nothing in changing ANYTHING about the actual functioning of the rifle. the actual gap is not whats important. the gap is simply an indication of the other stuff. its not like theres some magical buffer zone that the gap makes because the bolt and carrier are not touching. that gap is just a means of measuring where the rollers are. when you think about it logically, it proves itself.

p.s., the HK design doesnt need to be "headspaced" like typical bolt rifle. the bolt rests everysingle time right at the face of the chamber. its the same headspace even if you made your bolt gap .050. the round would still be chambered and headspaced correctly, but the rollers would not be pushed out to lock the rifle in place. the same thing goes for if the gap is too small. the rifle is definitely locked, thats not the issue. its locked in and has slack. so one must install bigger rollers, lp, new bolt, or repress the barrel to get those rollers to "float" in the right spot on the LP to time everything correctly. Most people when they add BG experience less recoil as everything is floating in the right spot.

DRAKEJAKE,

if you disagree with anything Ive said, please support your claim that a ground bolt is safe, and support it with your own facts on how the rifle works. I'll wait.

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COA #106121 COG #1000 NRA #148440199

Copenhagen is my anti-drug!




myco4you
Gunboards Member



44 Posts
Posted - 11/20/2006 : 09:46:25 AM
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jfowl31-Do not let this guy get under your skin.If he truly believes that his rifle is OK,there is no use trying to change his opinion any further.It is obvious that he is VERY hard-headed,and further persuasion is futile.That,or maybe he is one of those guys who craves confrontation.Either way,we are all just wasting time in trying to help this guy.
At this point,the creator of the rifle system could come on here and explain the situation,and this guy would still not believe that his rifle is not correct!


jklinstein
Gunboards Member



USA
20 Posts
Posted - 11/20/2006 : 10:44:26 AM
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Unlocked:
Download Attachment:
18.09 KB
Locking piece bottomed out on bolthead, NO FORCE on rollers, therefore NOT LOCKED. This can happen with a ground bolt head.
Download Attachment:
28.61 KB

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Edited by - jklinstein on 11/20/2006 10:47:19 AM


jfowl31
Gunboards.Com Silver Star Member



USA
713 Posts
Posted - 11/20/2006 : 7:51:14 PM
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quote:
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Originally posted by myco4you

jfowl31-Do not let this guy get under your skin.If he truly believes that his rifle is OK,there is no use trying to change his opinion any further.It is obvious that he is VERY hard-headed,and further persuasion is futile.That,or maybe he is one of those guys who craves confrontation.Either way,we are all just wasting time in trying to help this guy.
At this point,the creator of the rifle system could come on here and explain the situation,and this guy would still not believe that his rifle is not correct!

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Im with you... but part of the reason i come to this forum and others is to try and help others and learn something myself.

I gave it a good shot though, I guess if logic about how the weapon functions is not proof enough, without having Lt. General Don Juan Vigon here to explain his original design (or whoever first came up with the roller-locking system), maybe all hope is lost for this one.

oh well.......

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COA #106121 COG #1000 NRA #148440199

Copenhagen is my anti-drug!




drine
Gunboards Premium Member



USA
180 Posts
Posted - 11/22/2006 : 6:34:01 PM
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Is this the same weapon for sale now on CETMERIFLES?????????


jfowl31
Gunboards.Com Silver Star Member



USA
713 Posts
Posted - 11/22/2006 : 7:15:54 PM
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jklinstein's rifle is for sale over at cetmerifles... and he is very up front and honest about problems that the rifle has. I think quite honestly, he outta be selling it for more than he is... but thats just me. If anyone has the means to repress a barrel, it would be a really quick cheap way to have a nice rifle. If it were me, I'd throw that thing in the back of my gunsafe and wait for the prices to rise... i got an inkling these babies wont be too cheap for much longer.

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COA #106121 COG #1000 NRA #148440199

Copenhagen is my anti-drug!




tr6r
Gunboards Member



USA
91 Posts
Posted - 11/25/2006 : 8:38:54 PM
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Now I'am a little confused. My CETME had a ground bolt measured 1.827. The unground bolt from my CETME parts kit measures 1.823. Wich one should I use?









edited for spelling

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Edited by - tr6r on 11/25/2006 8:40:56 PM


jfowl31
Gunboards.Com Silver Star Member



USA
713 Posts
Posted - 11/25/2006 : 9:00:26 PM
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I've HEARD that there were some bolts sold and recalled by the seller that were shorter than the original bolts.

I don't think I'd use either personally, but its all your choice. Whats your gap with the ground bolt? I mean technically you can use either one, as long as you take into effect the difference in length while measureing you gap. But can you tell which side of the rollers (front or back) the new unground short bolt is shorter on? as in can you measure the length from the roller hole to he bolt face, and from the hole to the rear?



--------------------------------------------------------------------------------
COA #106121 COG #1000 NRA #148440199

Copenhagen is my anti-drug!




gw11
Gunboards Premium Member



USA
210 Posts
Posted - 08/01/2007 : 6:39:30 PM
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up for revamp


gw11
Gunboards Premium Member



USA
210 Posts
Posted - 08/01/2007 : 6:40:40 PM
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up to be saved
 
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