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Old 04-04-2013, 11:06 AM   #1
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Default HELP! Bent AK74 Folding Rear Trunnion [Photo Attached]

I need help guys.

I was putting the finishing touches on an Bulgarian AK74 folding stock build, and drilling/countersinking the rivet holes for the swell neck rivets -- but things went horribly wrong.

In short, I pressed too hard with the 12 ton press. I totaled the receiver and slightly bent the trunnion inward. I need to figure out a way to bend the trunnion back out. A BFH (big frackin' hammer) is not an option for obvious reasons.

I have no problem dropping $50 or less on a new trunnion, but finding JUST the trunnion is proving fruitless.

It only needs to be moved an 1/8th of an inch or less -- but the steel is strong.

Does anyone have any ideas? Links to tools? Know where to buy JUST the trunnion?
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Old 04-04-2013, 11:23 AM   #2
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I had one that was bent a little, I put the trunnion in a vise and heated it until I bent it back straight with a crescent wrench. No need to get it red hot.
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Old 04-04-2013, 11:58 AM   #3
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You crushed the rear of the trunnion at the long through rivet or tweaked the front arms at the short rivets? Big difference.
Bulgarian or Asian trunnion?

If all else fails>

http://www.k-var.com/shop/KR-001RT.html
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Old 04-04-2013, 11:59 AM   #4
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Simply get a bolt just long enough to fit between the ears of the trunnion and then thread a nut down to where it is flush with the end of the bolt then put the bolt and nut combo in between the ears and loosen the nut and itwill push them apart. A little heat to the bent side might be in order.
You can also use this idea to bolster the tangs when you are doing the countersink operation
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Old 04-04-2013, 12:04 PM   #5
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Quote:
Originally Posted by frameman View Post
Simply get a bolt just long enough to fit between the ears of the trunnion and then thread a nut down to where it is flush with the end of the bolt then put the bolt and nut combo in between the ears and loosen the nut and itwill bent them apart. A little heat to the bent side might be in order.
That can work for the tweaking of the front ear areas. If the long rivet area is crushed it is a much more difficult situation. All the sidefolder trunnions are a bit fragile. The asian ones more so.
All can be crushed/collpased out of shape at the long rivet area if care and observation are not used.
I guess OP will report where it is tweaked.
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Old 04-04-2013, 12:14 PM   #6
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Quote:
Originally Posted by AKBLUE View Post
That can work for the tweaking of the front ear areas. If the long rivet area is crushed it is a much more difficult situation. All the sidefolder trunnions are a bit fragile. The asian ones more so.
All can be crushed/collpased out of shape at the long rivet area if care and observation are not used.
I guess OP will report where it is tweaked.
From the photo he supplied it appears that only the ears where damaged. I hope it's simple for him. Too bad about the receiver.
Semper Fi to the OP from a former grunt machine gunner
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Old 04-04-2013, 12:19 PM   #7
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Quote:
Originally Posted by frameman View Post
From the photo he supplied it appears that only the ears where damaged. I hope it's simple for him. Too bad about the receiver.
Semper Fi to the OP from a former grunt machine gunner
Oh., OK initially I did not see a pic in the post. Looks like an easy fix to the ear as you note. Pic of the receiver might help to see how bad that is. The rivet tool crusahers are the way to set shoirt rivets or one of the builder jigs.
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Old 04-04-2013, 12:28 PM   #8
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I've done the bolt trick on one of my builds. The only problem was that the nut was trying to walk sideways as I turned the nut. I cured this by grinding the head of the bolt so it had a small "nub" on it to locate it in the trunnion rivet hole on one end, and a small ball bearing in the other. Worked great.
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Old 04-04-2013, 05:55 PM   #9
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First, I want to thank you guys for the responses. I like that I have received answers from three people that know what the frack they are talking about. I also like that there were different methods to the problem!

I am going to try the bolt method first... the heat method second... and the KVAR link third.

Quote:
Originally Posted by AKBLUE
The rivet tool crusahers are the way to set shoirt rivets or one of the builder jigs.
Do you mean the rivet tools adapted from bolt cutters? I do have them -- but I opted for using the AK-Builder tool and lacked the support between the ears of the trunnion. This is my first build, so despite having all the special tools you can think of, I don't have a "system of procedures" down yet. I was in a rush and didn't think about using the bolt cutter tool I have. *duh*

I have taken copious notes, videos and pictures along the way documenting the build, step by step, that will prove useful to others in the future.

Thanks,

USMC Patriot

PS: Semper fi, Frame man!
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Old 04-04-2013, 06:04 PM   #10
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Quote:
Originally Posted by USMCPatriot View Post
I opted for using the AK-Builder tool and lacked the support between the ears of the trunnion. !
You not doing it right
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The same administration who put "Assault Rifles" into the hands of Murderous Drug Cartels now seek to take them from you.
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Old 04-04-2013, 07:46 PM   #11
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Quote:
Originally Posted by Dan FS71 View Post
You not doing it right
I am assuming you hit the "post" button before you finished writing...

Could you elaborate on how to do it correctly?
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Old 04-04-2013, 08:17 PM   #12
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This is how I dimple all but the long rivet.



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Old 04-04-2013, 09:00 PM   #13
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Quote:
Originally Posted by USMCPatriot View Post
I am assuming you hit the "post" button before you finished writing...

Could you elaborate on how to do it correctly?
Nope, that was it.


Quote:
Originally Posted by AK shooter View Post
You are doing it right
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================================================== =========================
The same administration who put "Assault Rifles" into the hands of Murderous Drug Cartels now seek to take them from you.
================================================== =========================
How is that for common-sense Change?

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Old 04-05-2013, 10:44 PM   #14
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Cool. Thanks AK Shooter and Dan!
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Old 04-09-2013, 01:31 PM   #15
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Just a follow-up thanking everyone for their help. I was able to fix everything and completed the build! It isn't perfect, but it's an AK not a Swiss watch.

Right now, I am doing final assembly -- then I will take it out to one of the local gravel pits for test firing.
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