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Dunderway
03-11-13, 23:35
I have recently acquired a very nice SAR-1 and am trying to un**** a few of the things that Century Arms did to it. The major one is the welded BCG. I have searched around but have seen a lot of different numbers/opinions.

I'm sure that no one has the original Soviet TDP for an AKM, but if anyone knows for certain the following from something like a Fuller class or experience, it would be really helpfull.

- What size bit should the carrier be drilled with?
- What size bit should the piston be drilled with? Supposedly is should be larger than the carrier hole.
- What should the gap (in feeler gauges or thread turns) be between the piston collar and the front of the carrier?

I guess that's it. Any information or tips would be appreciated.

Thanks,

D
Peshawar
03-12-13, 00:06
Does this help? AK-Builder vid link (http://www.youtube.com/watch?v=S0hnyTzE2cw&feature=player_embedded)
Iraqgunz
03-12-13, 03:29
Apexgunparts.com has lots of AK stuff in stock. If you are concerned about the carrier, just toss it and get a good one. From what I recall (and I may be wrong) they were designed to have some play to account for variations in the building tolerances.
eodinert
03-12-13, 05:01
The words 'feeler gage' appear nowhere in the AK maintenance manual :D
Dunderway
03-12-13, 15:11
Does this help? AK-Builder vid link (http://www.youtube.com/watch?v=S0hnyTzE2cw&feature=player_embedded)

Yes it does, thank you. I will probably just follow his instructions, but I have heard some conflicting info on hole sizes.

My BC should work fine with a new piston. I was finally able to find the welded hole after some polishing and cold blue. I know this gun will never be a high dollar collectors piece, but it looks to be almost unfired and all of the numbers match, so I'd like to get it into spec.

Feeler gauges and AKs gets a laugh, but these guns had to have been intended to be built to a set of specifications, and this gun does not meet them. As IG said, there should be play in the piston so it doesn't drag/crash into the gas tube/block.
Peshawar
03-12-13, 15:28
Ak-builder has all the parts and tools to accomplish the task. Check out the gas piston and tools pages of his site, and you should see all you need. Buy with confidence from Curtis, I've got a ton of his stuff and it's all quality. :)
halmbarte
03-12-13, 16:01
When I changed mine (CAI welded bolt carrier/piston) I turned the piston till it was hand tight, then backed it off 1/2 turn.

Drilled the piston and carrier with a 3mm drill bit, inserted the rivet, flared the ends, and filed it smooth. The completed bolt carrier and piston had a little wiggle but wasn't floppy.

H
Dunderway
03-12-13, 19:58
When I changed mine (CAI welded bolt carrier/piston) I turned the piston till it was hand tight, then backed it off 1/2 turn.

Drilled the piston and carrier with a 3mm drill bit, inserted the rivet, flared the ends, and filed it smooth. The completed bolt carrier and piston had a little wiggle but wasn't floppy.

H

This is where the conflict comes in. I have read several sources that claim the piston should be drilled at 3.5mm and the carrier at 3mm. AK-Builder shows drilling them both at 5/32 (~4mm).

I'm sure that I'm overthinking this, but it will not cost me anymore to do it right.
Dunderway
03-12-13, 20:00
Apexgunparts.com has lots of AK stuff in stock. If you are concerned about the carrier, just toss it and get a good one. From what I recall (and I may be wrong) they were designed to have some play to account for variations in the building tolerances.

IG, are AKM BCGs the same/similar to that of an AR? Meaning that you can swap a compatible in-spec BC as long as you keep the original head-spaced bolt, without having any issues?
Iraqgunz
03-13-13, 02:36
I have actually had some BCG's that would not lock up correctly in other AK's when swapped around. It appeared that the lugs of the bolt were interfering with the lock up.

The carriers themselves were a non-issue. When I was stripping guns and repairing them I went to great lengths to ensure that I matched the same parts from the same country.


IG, are AKM BCGs the same/similar to that of an AR? Meaning that you can swap a compatible in-spec BC as long as you keep the original head-spaced bolt, without having any issues?
Dunderway
03-22-13, 21:42
Thought I should update this:

I purchased a NOS Romanian bolt carrier at a good price. The piston is properly riveted while having at least 1mm of thread between the collar and the end of the bolt carrier, and wobbles like all-get-out. It functions smooth as butter, as it was intended to.

My original carrier and a few WASR carriers should be going to the drill press shortly. I will gauge everything on this MilSpec carrier and modify the Century F-ups accordingly. I will also try and post the steps and measurements here if anyone is interested.