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Discussion Starter #1
HI,
I'm new here and was refered by RU Shooter from over on the Cast Boolits board. Looks like I sure found the right place for answers to Military rifle questions. I have a question about a 24/47 I bought. It sure looks like a nice rifle but have one concern. At first I thought I didn't get all the cosmoline out of the chamber but seems like I did. I scrubbed with Ed's Red and Kroil until it was squeeky-Kleen. Now my problem is that the chamber seems a bit short. I can chamber a load in it but the bolt closes down real tight and the cases come out shorter. I am using RCBS Dies and Lee Dies to compare against and see no difference in sizing length with those. My other 8mm is a Turk and it's a real cast bullet shooter's dream. Has anyone else run into their barrel being short chambered on these rifles?
 

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Originally posted by Newtire

Has anyone else run into their barrel being short chambered on these rifles?
Not in a rifle properly chambered for 8mm Mauser.

Did you disassemble the bolt and clean it thoroughly also? Check to make sure it's chambered for 7.92x57mm or 8mm Mauser. Check your ammo to be sure it's with in spec. Try some different commercial or surplus ammo to see if you still have the problem.

Also, I recommend you complete the safety check on the link below.

http://www.mausershooters.org/k98k/k98kframe.html

Click on "Shooting Clinic" located on the left column. Then, click on "Mauser Safety Check" on the top of the page.

Get a set of headspace gages and measure the headspace. Sounds like you need a "go" and "no-go" gage. It may be out of spec.

Go gage:
http://www.midwayusa.com/eproductpage.exe/showproduct?saleitemid=565357&t=11082005

No-Go gage:
http://www.midwayusa.com/eproductpage.exe/showproduct?saleitemid=572377&t=11082005

Field gage:
http://www.midwayusa.com/eproductpage.exe/showproduct?saleitemid=563880&t=11082005

You may want to do a chamber cast and measure the results to check the specs on the chamber. See the link below.

http://www.surplusrifle.com/shooting2005/chambercast/index.asp

If you're not comfortable doing these tasks, take it to a gunsmith.

Regards
 

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Discussion Starter #3
Short Chambered Mauser

Thanks for the exaustive reply Tig. I have a No-go gauge but not a "Go" gauge. I will have to put it off for a bit to get around to it but will get some cerrosafe and try that out. I slugged the bore and it's 8mm (I forget exactly what it was-.325" I think) and the bolt closes on a 8X57 case but not without difficulty. I am thinking maybe it wasn't finish reamed possibly. The bore looks new. But, I'll check out the safety check links after work tonight. Thanks for all the help. Now I have something to follow. I'll let you know.
 

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I've had some tighter than others. A quick chase with a finishing reamer might be in order, but not before you try the 'go' gauge.
 

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Newtire,

If you do a chamber cast, check the shoulder angle. Use a caliper to measure carefully the variables below.

The math formula for the chamber shoulder angle is:

x = arctan((a - b) / 2c)

Where:
a = diameter of shoulder base
b = diameter of shoulder top
c = height of shoulder
x = shoulder angle in decimal degrees

Alternatively, you can use the formula below. It may lend itself to more precision, because it will be easier to measure a distance along the shoulder diagonal. Use both methods to check for repeatability. There’s always some likely error when taking measurements to 0.001”.

x = arcsin((a – b) / 2d)

Where:
a = diameter of shoulder base
b = diameter of shoulder top
d = length of shoulder diagonal (hypotenuse)
x = shoulder angle in decimal degrees


Then convert decimal degrees to the Deg-Min-Sec form.

There's been some debate on another forum as to what shoulder angle the Yugo's used when they re-arsenaled. You should get a result between 18° and 21°. Let's us know the results. Thanks
 

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TRY...

Before you go reaming that chamber any more, if you can get ahold of a couple of other 24/47 of M-48 bolts (K-98 won't work because those are "intermediate length" actions) and swap them around to see if things don't loosen up with another bolt. Perhaps some of your range buddies would let you borrow one to try.
Who knows - he might have excessive headspace, so you could swap and both come out daisies!

I got a "threefer" of 24/47s from Century a while back, and a bolt from one of them will not even close on the EMPTY chamber of another!
It works fine on the rifle it came in, though.

Remember; these rifles were frequently if not usually cobbled together by the Yugo Armorers from spare parts and parts cannibalized from guns that were beyond repair following WW-II, with newly manufactured parts inserted here and there where needed.

Do the last 3 digits of your bolt match the last 3 of your "Old" (original; usually on the right side of the receiver ring near the stock line) serial number? That number (sometimes 4 dig.) is usually stamped into the butt stock as well.

If not, then you well may have a mis-matched bolt.
That's what it sounds like to me, frankly.

If the bolt face is rough and cruddy, a Gunsmith could turn it down enough to restore proper head space and clean it up at the same time.
Either that or you could try to find another bolt body, shorter by a couple of thousandths, that works better.

Do you have a replacement M-48 barrel (you can usually tell by the hooded front sight)?

They might have wound it in a little too tight - but I doubt it.
The Yugos used a peculiar "Safety breech" system that requires a lot of precision machining and fitting, and they were usually pretty fussy about it.



If your barrel is in good condition, I would be very hesitant to go reaming in it - it's a lot easier to lengthen HS than it is to reduce it - and with that Safety breech system, you do NOT want to go trying to turn and re-set the barrel!
(They are a real bear to get off, too!)

Bolt bodies being a whole lot cheaper than barrels, I would recommend that you go that way first.

Although HS can be extended by polishing a little off of the rear of the locking lugs, I hate to do that as you are apt to remove the "case hardening" layer of extra hard steel that is only a couple of microns thick (if that) and the lugs will start peening and wearing back on you. Not good!
Besides; that is NOT a job for amateurs!

As a reloader, I try to use good surplus ammo within military specs as a "standard" to set my dies up.

If you are going to be using any kind of live round to check head space, leade length or whatever in your rifle, any place other than the range, be sure to gut the bolt body out before you put that round in - and even then be VERY careful!



Even at a range with the muzzle downrange, you do NOT want to touch one off with a bolt that is not completely locked up!
Despite the Mauser's ingenious firing pin safety, a grain of dirt, a burr on the FP hole, or an insufficiently seated primer can touch off on you when you least expect it - especially if you are trying to crowd a recalcitrant round into a tight chamber!
 

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Uncle Jaque brought up some important points. First, is your rifle all matching? I assumed it was. You know what they say when you assume something.

Also, don't do any chamber reaming or metal work until you've made a complete assessment of the problem. Swapping out bolts is part of the problem solving process.
 

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Discussion Starter #8
Mismatched bolt

:eek:

I checked the numbers against each other and looks like the action matches the stock but not the bolt. Also the barrel does have a hood on the front sight. The numbers on stock/action are #1380 while the number on the bolt handle is #1135. So, if anyone out there has the exact opposite, we should just trade...hey worth a shot huh...

Actually, you guys are great. I am going to order some cerrosafe and a "go-gage" if I can't verify using the cerrosafe. It looks like a real sturdy rifle and a nice one at that so if it proves to be short in the chamber and can't find a matching bolt, I may just have the guy at the gunshop ream the chamber a tad longer.

Thanks for all of your help.
 

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I am going to order some cerrosafe and a "go-gage" if I can't verify using the cerrosafe. It looks like a real sturdy rifle and a nice one at that so if it proves to be short in the chamber and can't find a matching bolt, I may just have the guy at the gunshop ream the chamber a tad longer.
You will need a “go” gage. You can’t check headspace with a cerrosafe cast.

I’ll assume you intend to keep that bolt with the rifle. Then, if everything checks out during the Mauser Safety Check and everything with the bolt and receiver is OK, check the headspace with the “go” gage. If you confirm what you already know with the “go” gage, then do a cerrosafe cast to determine the chamber shoulder angle and if anything else is out of spec in the chamber and throat.

If you ultimately decide to ream the chamber, make sure you get the correct reamer that matches the shoulder angle of your chamber.

There are 8mm Mauser chamber reamers out there, in use by gunsmiths, that are cut to both the current and obsolete SAAMI 8mm Mauser chamber spec. The question is, what reamer is your smith using? For the 8mm Mauser, the obsolete SAAMI chamber spec had a chamber shoulder angle of 20° 48’. The current SAAMI chamber spec has a chamber shoulder angle of 19° which is closer the original German WWII era 8mm Mauser chamber spec of 19° 6' 2.8''. I believe the current CIP (european equivalent of SAAMI) 8mm Mauser chamber spec matches the German WWII era spec. Ideally, everyone should use current CIP spec reamers and gages, but they are not that available in the USA.

I suspect your chamber shoulder angle is closer to 19°. Confirm that with the cerrosafe cast. Don’t ream the chamber with a 20° 48' reamer if your shoulder angle is 19°; use a 19° reamer. Vice versa if your chamber shoulder angle 20° 48’.
 

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Since it's bolt is already not matching before you go reaming try another bolt.
 

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HS Guages

I've been told by some who seem to know that sometimes even if a "no go" guage will chamber, as long as it's a wee bit tight to close the bolt on the chamber may still be within "battlefield specs".

Some of the military rifles, particularly the .303 Enfields, intentionally cut their chambers on the sloppy side to allow for dirty or dinged up ammunition. They didn't care much if the cases got stretched or ballooned out somewhat in firing, as they usually were not going to reload them. So a chamber that will swallow a NG might be safe enough to shoot, as long as you just neck size the cases if you reload them and keep them separate and dedicated to that particular rifle.

But if your bolt will close on a "Field gauge", then headspace is sufficiently excessive that you might risk a head separation or other nasty problem upon firing.

When you get all 3 gauges, you can offer to check all your buddy's 8mm HS with it - and when you find a 27 or 48 with excessive HS, try swapping bolts. You might both come out winners!

Have you contacted the place you bought the rifle from, newtire?
Unless it was a "U-fix-'em" or some such, they might be willing to swap your bolt out for another one. wouldn't hurt to ask.
 

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I have a mauser in 8x57 that will not close on a go-guage, but will close on a round. I'm not about to have it re-reamed - it has a tight chamber and I now know it. Since there are variations (all within spec) among ammo, have you tried another brand of ammo? Have you simply tried sizing down some brass with the die tight up against the shellholder?
 
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