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Posted: 4/26/2010 11:53:46 AM EDT
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I have an A3 upper that must have been damaged while in the vice,
The bolt carrier starts out fine as you push it in, but then gets really tight when about 1/2 inch from closing, (please no "that's what she said" jokes) and the rear of the BC eventually ends up with one side touching the rear of the Upper instead of riding in the middle. I discovered this when the rifle short stroked immediately following assembly. I checked the BC with another rifle, and it's fine. Anyone know a trick to "straighten out" a crooked, or slightly crushed upper? |
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1/2" from the face of the carrier to face of the barrel extension tells me that the gas tube maynot aligned with the carrier key correctly.
Simply, with the carrier that deep in the upper receiver, if the receiver was squashed in, you should be having problems with the travel starting just a few inches in, not the last inch. Also, could be that the barrel extension is not lined up correctly as well (center section between the ramps not centered on the the upper lug, and the bolt binding on entry to the extension). Furthermore, could be that the bolt has not mated to the barrel extenion lugs, since the last inch of travel is also when the bolt is cam'g into the locked positon. |
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Yeah, I'm glad to spread the pain, ha ha
Here's more info, I did use a clamshell type vice block, but this particular upper has been part of several different projects. It was in the bottom of my toolbox, so I put it together. When the rifle short stroked, I, -Checked the gas block alignment with the hole, -checked the gas tube alignment, (thats when I noticed the Bolt carrier was not moving freely.) -completely disassembled the upper to confirm that the bolt carrier/ upper receiver were working together. That is when I could see very clearly the way the Bolt Carrier was behaving in the receiver. So............. I ordered a new upper! But......... I'm not giving up!!! I have a very fat neighbor who I will ask to step on the receiver after a few beers. If that does not work, maybe I will have it chromed and hang it around my neck when I go out on Saturday nights. |
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I picked up a slightly tweaked upper real cheap off of a seller on GB awhile back
I use my slightly squashed upper in a dedicated .22 and it works perfectly fine for that. if you have one of the .22 adapter kits, give it try and see if it functions before you trash the upper |
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I spent some time last night with just the bolt carrier and the stripped upper receiver,
sliding the BC back and fourth, looking at how the rails of the BC contact the receiver. It is amazing how little deviation is needed to skew the BC off to one side. I think the receiver is deformed inward just below the ejection port, about 1/2 an inch from the front of the port. It is so slight that you cannot see it, but you can identify the spot by watching the rear of the BC start to move off to one side as it travels forward. I ordered a new upper for my current build (16 inch 6.8spc) but I think this upper may be used for a left side charging handle project. It's always good to have a piece of "practice stock" for the lathe. |
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