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1/22/2020 12:12:56 PM
Posted: 2/16/2006 12:06:53 PM EST
First of all I would like to thank everybody here for sharing their knowledge - great site and resource.

Now for my problem...

I was about ten seconds from pushing the retaining pin for the gas piston out of my Polish bolt carrier (to replace with US piston) when I noticed two tiny hairline cracks traveling from each end of the pin to the end of the piston opening. I have no clue if I did this or it came this way from SG, the cracks are real hard to see.

I had an AK "expert" look at it and he told me to furrow the cracks and TIG weld them back together. The guys at the welding shop seemed to think it was no big deal though they said they would probably have to re-tap the carrier because when they perform the welding the threads will get damaged.
The fee for doing this is around $75.00 providing the thread pitch can be matched from their shop.

Option 2 would be spend the same amount of money on a new bolt carrier and replace the damn hand grip.

Would mixing a new bolt carrier with my used piston and trunnion effect fit, function etc? I could live with the numbers not matching providing it ran right. Anybody have any insight into this?


Link Posted: 2/16/2006 1:05:32 PM EST
Link Posted: 2/16/2006 1:54:38 PM EST
[Last Edit: 2/16/2006 1:56:36 PM EST by uxo2]
TIG it.....or Heli-arc
This way it gets a GOOD weld especially if he is a professional welder..... you will also maintain all matching number like before....
Use the old piston to help clean up the threads...Just grind flat on two side of the old piston 180deg apart to help remove any metal shavings.Kind of like a tap would look like but 2 sided instead of four...If the shop will tap it fo you then let them....They most likely have the right tools.
Since your not concerend about the numbers game then replace it....
good luck finding a Polish carrier....And if you do...It might cost more than the fix.
If you don't find a Pol...There might be fitting issues..

Link Posted: 2/16/2006 2:49:40 PM EST
Thanks for the responses... I'm feeling much better about trying to get the bolt carrier repaired. The shop I took it to specializes in TIG and Heli-arc so I should be in ok shape - I will know by next week. Interesting problem seeing how I would not have even known about the problem until the carrier/piston failed down the road.

Thanks again!
Link Posted: 2/16/2006 3:44:07 PM EST
Link Posted: 2/16/2006 5:16:10 PM EST
[Last Edit: 2/16/2006 5:17:01 PM EST by ozzy_the_nuke]
I would get an AMD65 carrier from heddonpal.com here for $15, since you plan on replacing the piston anyway. I have ordered from Heddonpal a few times and it has always been good.
Link Posted: 2/17/2006 4:17:12 AM EST
I had the same problem with a Polish kit except mine was only cracked on one side.

I exchanged it for a new kit. That's the option I'd go with if you have the choice.

The new kit turned out to be in 10 times better shape than the old one. I can barely tell the thing's been fired. Also, the new carrier doesn't seem to have a pin for the gas piston or at least I can't see the thing.

Link Posted: 2/17/2006 4:39:03 AM EST
have the bolt carrier beveled and tig welded with as low of heat as possible. have them rethread it there will be a small amount of distortion .I'm a welder by trade to bad yor not a local guy i'de do it for free.R1150R
Link Posted: 2/17/2006 5:37:41 AM EST
welcome to the board

you have 2 options

install new piston and weld it

change out the carrier you cant change the bolt but if they want any kinda money to weld it
just change out the carrier with a new 1 they are fairly cheap ($20)
Link Posted: 2/17/2006 10:43:49 AM EST
Great advice on everybody's part and thanks for the welcome.

Right now I have the repair on hold because I am actually trying see if I can exchange it with SG (Thanks tyler2you) I think this is a long shot because it has been about sixty days since I got the kit.

Thanks for the offer 1150R, I would feel better about the repair if the welders were gun guys.

If the new piston was welded to the carrier how does that affect the need for the piston to have some play at the connection? Everything else about this build is going top notch, so I would be dissappointed if I ended up with a dog of an AK because the carrier did not work right.

Again, what kind of problems could I expect with a new bolt carrier say from an AMD65 mixed with my Polish bolt and trunnion. Does the bolt wear into the carrier over time or is the carrier less important as far as matching worn parts together. What a saga - Geez!

Thanks again

Link Posted: 2/17/2006 7:59:05 PM EST
The AMD 65 will match fine. The parts are standardized and the tolerances are loose. If you have good alignment between the front trunnion and the receiver, piston wobble isnt necessary. Some of my pistons wobble and some dont. You can check the alignment by assembling the rifle without the gas tube and checking how well the piston lines up with the gas block. If the alignment is good (the piston goes into the port without binding), you shouldn't have any problems with a welded in place piston. You may even want to go ahead and try it the way it is (cracked). Your ammo budget will probably break before the gun does. If it breaks, I wouldnt expect any serious damage. It will probably just jam up. You could then replace or repair it at that time.
Link Posted: 2/18/2006 4:50:25 AM EST
Thats what I needed to hear! thanks Ozzy

Its not an AR its an AK
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