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Discussion Starter · #1 ·
This is the continuing sage of the bolt problems of my EM352 (NDM-86). The problem is that it had the firing pin tip modified to stop it piercing primers before I bought it. This seems to have created the problem that it will no longer fire milsurp ammo with hard primers. It fires the 1st & 2nd rounds - then only lightly bruishes the primers after that. Have been fortunate to find a Russian TIGR firing pin & return spring - but they won't fit inside the Norinco bolt. The FP hole in the Chinese bolt is a slightly smaller dia hole than the TIGR's. Next stage is to source a 308 TIGR bolt & try that, but I don't know how that will affect headspacing. Does anyone have any other ideas please?
 

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You will need to have the Chi-com bolt modified to accept the russian pin and spring. Any Good lathe man will be able to do it for you. The bolt stem is a bit on the hard side and a High speed steel reamer won't last too long. I used one to open up my chi-com bolt and it did the job, but she squeeled the whole time, it may not be able to cut another one.
The different size holes between the tiger and the chi-com boltface MAY not be an issue if the difference is but a few thousandths. Otherwise the pin diameter can be reduced by a competant (SP?) lathehand, that also understands the function of firing pins and the need to keep the nose spherical.
I have made a few pins for the NDM/Drag.... it is tedious work, but can be done.

Kerry

P.S.
The fact that it fires a couple rounds and then only dents those after, may indicate a burr or foriegn matter in the bolt.
 

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Discussion Starter · #5 ·
I used one to open up my chi-com bolt and it did the job, but she squeeled the whole time, it may not be able to cut another one.

Kerry

P.S.
The fact that it fires a couple rounds and then only dents those after, may indicate a burr or foriegn matter in the bolt.
Hi Kerry,
Thanks for the reply. Does the hole along the inside of the Chinese bolt stem need to re-drilled for the full length..or just the length of the TIGR return spring?

Have checked the inside of the bolt stem for obstructions - its clean as a whistle. The firing pin is totally free to travel. The rifle works fine with Aussie F4 ammo which must use a softer primer. Problem is there's not much F4 around any more.
 

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308nutt,
you only ream as deep as needed to get the spring in, and a sufficiant diameter to give the spring a little room to expand when it compresses. If you can wait a day or two I will get you some numbers you can use as a
basis to have yours done. I used a reamer because you don't want a rough surface inside the stem to grab at the spring as it tries to compress, so when
you find someone to do it, don't have them just drill it out. It needs to be drilled and reamed. Carbide may be the better option versus High speed steal.
(HSS)

Kerry
 

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I would make real sure what you have can't be fixed before jumping in and modifying the bolt for some other pin. Sometimes there's a way to get the pin to extend out a bit farther without much work. Look for someone that can do this before changing your bolt, if it can be done at all of course.

Good Luck
 

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I would make real sure what you have can't be fixed before jumping in and modifying the bolt for some other pin. Sometimes there's a way to get the pin to extend out a bit farther without much work. Look for someone that can do this before changing your bolt, if it can be done at all of course.

Good Luck
I would agree, except it sounds as if someone has munched the tip. Which if that is true , due to the taper that is directly behind the tip it would be extremely difficult to get it to extend any further. It could be done but it brings up other issues....He would be better of with a spring loaded FP in the long run. It would give him a wide choice in commercial ammo.
He just needs to find a competent lathehand.

308, I sent you an e-mail.
 

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Discussion Starter · #12 · (Edited)
The bolt has now been drilled/reamed as per Oh Boys directions. Should be able to rangeshoot it in the next couple of weeks to try it out. I'll post a report.

Thanks to Oh Boy for your advise!
 

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The bolt has now been drilled/reamed as per Oh Boys directions. Should be able to rangeshoot it in the next couple of weeks to try it out. I'll post a report.

Thanks to Oh Boy for your advise!
Wow...That was pretty quick 308 !!

If you have not done so already....

Before you go to the range and test fire that rifle , You NEED to check to see how much the new firing pin protrudes from the bolt face. If it is too far, you will pierce primers, if it is not far enough, light primer strikes, and you will have the same problems as before.
 

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Discussion Starter · #14 ·
Range Report

following on from previous postings...
the bolt was drilled & reamed just far to allow fitting of the Russian firing pin/retaining spring. However the firing pin protrusion was more than double 'Ohboy's' allowable dimension- so the front of the pin was shortened & the tip profile exactly copied by the gunsmith. (I warned him to remove the metal from the back of the pin - not the front, but he missed my email).

Took the EM352 (NDM-86) to the range last week & test fired 5 singlely loaded rounds using 308 SA R1M1 ammo...1st shot mis-fired (shallow primer penetration) / 2nd, 3rd, 4th & 5th fired normally with good primer penetration. No pressure marks or primer piercing problems..all appeared normal. Then loaded 5rnds into the mag..1st rnd mis-fired (shallow primer penetration), the rest of the rnds fired normally. So it went on...each 1st round loaded mis-misfired but the rest fired normally. There were no signs of excessive pressure or primer problems at all.

Although these mis-fires still seem disappointing - I've actually made progress by fitting the Russian firing pin /return spring, because any safety issues should have gone now. Previously the rifle wouldn't fire SA R1M1 ammo at all but now it only mis-fires the 1st round.

Any ideas on what can be causing the 1st round mis-fires please?
 
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