[MisterSuzuki]

While removing the front trunnion rivets, on my last one, I somehow had a brain fart due to a stubborn/worn drill bit, and drilled about 1/4 to 5/16" into the barrel.

So my question is, is all lost, and dangerous to continue with my build (except maybe build a dummy gun)?

i was thinking if I thread the trunnion, as well as the area where I drilled into the barrel, and use a longer screw, I "might" still have a safe weapon.

Any comments would be appreciated......if all is lost, anyone have an extra front AMD assembly?

 

[Rule .308]

I did that on my first AMD build as well, although it was much shallower than what you've got going there. If it were mine I would scrap it and start over. I, on the other hand, practiced my welding on similar holes in some 1/4" stock until I got the results that I wanted and then welded the divits in my barrel and ground them down again. I figured that the damn big notch in the barrel for the retaining pin was as good of an indicator as any for how deep you could drill into the barrel without it blowing up in your face. The deepest hole I had going was in the area of .200". Yours are in the area of .250-.3125, I would measure the barrel and see how thick the barrel material is around the chamber, see how deep the groove for the retaining pin is, and then base my decision on that. With Tapco selling AMD kits for 60.00 you think you'd be able to score a barrel fairly cheap though.

 

[MisterSuzuki]

I'll check how far I went in....I should have paid a little more attention.

I did check with Tapco, the $59 kit sale is over, and now its at $79. But they do have the front AMD65 assembly for $24.99, so I"ll be going with that route.

Either way, i'll probably try to salvage the trunion, and the other parts, or save them for a dummy build.

Oh well, that's what I get for getting a little too ahead of myself.

Thanks for the info....but i'm pretty sure I went at least 3/4 into the barrel.

I did that on my first AMD build as well, although it was much shallower than what you've got going there. If it were mine I would scrap it and start over. I, on the other hand, practiced my welding on similar holes in some 1/4" stock until I got the results that I wanted and then welded the divits in my barrel and ground them down again. I figured that the damn big notch in the barrel for the retaining pin was as good of an indicator as any for how deep you could drill into the barrel without it blowing up in your face. The deepest hole I had going was in the area of .200". Yours are in the area of .250-.3125, I would measure the barrel and see how thick the barrel material is around the chamber, see how deep the groove for the retaining pin is, and then base my decision on that. With Tapco selling AMD kits for 60.00 you think you'd be able to score a barrel fairly cheap though.

 

[yosuthnmasa]

But they do have the front AMD65 assembly for $24.99, so I"ll be going with that route.

Are we talking about the barrel and trunnion for $24.99? If you're going to scrap it, isn't it worth it to atleast give it a shot and weld it up? I mean, if you get a nice puddle weld in there. It oughtta fill it in quite nice. I would then finish the build, and tie the thing to a tree and fire it with a string. If it blows up you can always replace the barrel and trunnion with the parts. Hopefully it wouldnt blow the entire gun up.

Or, you could go the safe route and just replace the barrel and trunnion and not worry about getting blown up.

 

[MisterSuzuki]

Youth,

What do you guys use to for a puddle weld? All I have access to currently is an Arc welder I bought from Home Depot many years ago, and an oxy/acetylene kit, with empty tanks.

Seeing how everything came out nice....except that last hole, I'll try to finish it up, and do the tree thing for several magazines, just to be sure.

But I think to get a puddle going, I'll certainly need more practice....as I have used an oxy/acet torch in almost 10 years.

Are we talking about the barrel and trunnion for $24.99? If you're going to scrap it, isn't it worth it to atleast give it a shot and weld it up? I mean, if you get a nice puddle weld in there. It oughtta fill it in quite nice. I would then finish the build, and tie the thing to a tree and fire it with a string. If it blows up you can always replace the barrel and trunnion with the parts. Hopefully it wouldnt blow the entire gun up.

Or, you could go the safe route and just replace the barrel and trunnion and not worry about getting blown up.

 

[yosuthnmasa]

Personally, I dont have much experience with it myself. I did weld up a hole that I misdrilled in my receiver the other day. WinnR, I think is the one that does all of his rails with a puddle weld. He would be a good one to get specifics on this. He uses a MIG, though, with Flux core I believe. As far as I can tell, you would turn the volts up pretty high and just continue feeding the weld until it puddles up in the hole. Personally, if youre going to do this I would practice on some other holes first. Or, like many others, take it to your local muffler shop and give em a few bucks to do it the right way. Its not like its a huge job, just a small hole that need to be filled in. Many places might even do it for free. If I was in this situation without a MIG this is probably what I would do to avoid the hassle of getting one and having to practice and all. This way you don't have to scrap your build and can continue. I would double check with some of the other guys just to make sure they think this will hold and will be safe.

 

[Winn R]

OK my 2 cents.

Pull the barrel out to see it and allow access to the hole.

Tig would permit better control at filling the hole.

finish it off smooth to get the barrel back in. A real pita.

or chunk the barrel. 5/16" is a long way in.