AR Lower Repair

K

kevlars

New member
A friend of mine called me tonite, because he knew that I just got my hands on two new RRA stripped lowers. He told me that his bro-in-law was attempting to remove or reinstall, I don't know which, one of the pins that hold in the trigger guard. Well, I think you know what happened, he broke one of the ears off. /ubbthreads/images/graemlins/angry-smiley-055.gif So, he wants to buy one of mine.

My question is this, is there any way to repair this and make the lower serviceable again?? I have read about people useing JB weld or something similar to do this. Is this possible to do? /ubbthreads/images/graemlins/confused1.gif

kevlars

P.S.-- Honest, it wasn't me who did this, I haven't built my AR yet. Have the parts, gonna happen soon. /ubbthreads/images/graemlins/grin.gif
 
I assume the "ear" that was broken off is one side of the lower where the roll pin goes through the receiver to hold the bottom portion of the trigger guard on? If so, you could repair it with JB weld I suppose. I would be more inclined to have it professionally TIG welded.

Either way, the damage does not have an adverse affect on the lower receiver's integrity and it is still servicable, albeit without the lower portion of the trigger guard in place, and the obvious cosmetic detraction. The lower receiver of an AR is essentially a housing for the trigger group, a grip, and a place to mount the upper. It handles no pressure or other stresses.

If you do repair it by whatever method just check for cracks elswhere on the lower. If the proper size roll pin or drift punch was used it should never have broken in the first place. Maybe a little extra "oomph" with the hammer and a wrong size punch caused other damage.
 
He could dremel off the broken area smooth, then install a MIAD grip. If he gets the MIAD complete kit, one of the front straps includes a built in trigger guard. It could still be secured in the front and I dont think the rear would really need to be pinned at all.
Not perfect but an easy solution.

I just picked up a Magpul enhanced trigger guard today for a build and I'm a little nervous about installing it for just this reason.
 
Quote:
If the proper size roll pin or drift punch was used it should never have broken in the first place.



They're easy to break. I punched mine out to put on a winter trigger guard, and it was tough going (and I had the correct diameter punch). The way to do it without breaking the lower ear (and it's easy to break) is to drill a hole slightly larger than the pin into a piece of aluminum or wood, and keep the ear tight down on the backing as you drive the pin out (into the hole). If you try it without any back-side support, you'll probably regret it.
JB Weld should fix it. The lower is forged 7075 aluminum alloy and it's not weldable, as far as I know. If it's a 6061 billet lower, you could try and TIG it. The broken off ear is so small, I think it would melt, but somebody that's really good with tiny parts might be able to do it. Than the anodizing is shot, though. /ubbthreads/images/graemlins/confused1.gif
I think JB Weld would be just as good, it's not going to have to take much of a load.

He's not the first person to do that, trust me.
 
The TIG repair was just a thought. I can weld steel only marginally, and aluminum not at all. Didn't know that wasn't realistic, not trying to give bad advice.

Part of driving out pins is to use a bench block, despite the proper size punch. I have had several roll pins that were "difficult" to remove and appeared to have been stuck in with finish. I always used a bench block since breaking one would have gotten me in a lot of trouble since they weren't mine.

If welding isn't an option as stated above, JB Weld and a file would be my suggestion too.
 
Even with Heli-arc or TIG, aluminum that small is really difficult, but not impossible.

I'd call the factory that made the lower and ask their opinion for a repair... They may say JB is the best way or have a better method..
 
that is the worst part for me while putting lowers together, as stated use the proper tools and it should go fine. They can break very easy putting the pressure down on them without support under them. i would say JB weld as well them it would make a good canidate for a camo job Ron
 
7075 welds just fine with TIG. It is not approved for structural aircraft parts because the weld is fatigue prone. In this instance fatigue should not be a problem.

Jack
 
Quote:
7075 welds just fine with TIG.



I stand corrected. I did some research and I was wrong. They do state it will always crack when welded, but it can be done. You'll still lose the anodizing around the welded area, though, and that little ear will melt during the process.
But it can be welded. /ubbthreads/images/graemlins/wink.gif

Have fun with that.
 
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