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Started By
Message
Weird; I got a bent/bowed bolt carrier
Posted on 4/8/24 at 11:22 pm
Posted on 4/8/24 at 11:22 pm
I was throwing a 7.62x39 upper together from parts, ran into a problem... the BCG wouldn't go all the way into the chamber. Would stick about 2/3 of the way in. I have several other builds in that caliber, I did the ol' swap test- the other BCGs fit in everything, this won't fit in any. I have extra BCGs so I swapped the bolt into another carrier, and it fit and cycles nice.
I thought it might be the gas block, so I removed that, and still- the bare carrier would not go in when lined up. I set the carrier on a table to compare to the others, and that's when I spotted it: the damn thing is bowed. On a flat surface, only the rear edge touches the table, the rest of the rear comes up at an angle. Once you see it, it's pretty obvious, I just never thought to check that before (never heard of that being an issue).
I got it from Primary Arms, but well outside of the return window (I found the order from last September). I sent them an email explaining the issue, but I don't expect anything this late.
Fwiw it's this:
Precision Defense 7.62x39 Complete M16 Bolt Carrier Group - Nitride
SKU: 7.62x39-BCGBN
Is there anything that could be done, outside of removing all parts and scrapping the carrier? Anyone ever have a bent carrier? This was unused, just a spare part.
I thought it might be the gas block, so I removed that, and still- the bare carrier would not go in when lined up. I set the carrier on a table to compare to the others, and that's when I spotted it: the damn thing is bowed. On a flat surface, only the rear edge touches the table, the rest of the rear comes up at an angle. Once you see it, it's pretty obvious, I just never thought to check that before (never heard of that being an issue).
I got it from Primary Arms, but well outside of the return window (I found the order from last September). I sent them an email explaining the issue, but I don't expect anything this late.
Fwiw it's this:
Precision Defense 7.62x39 Complete M16 Bolt Carrier Group - Nitride
SKU: 7.62x39-BCGBN
Is there anything that could be done, outside of removing all parts and scrapping the carrier? Anyone ever have a bent carrier? This was unused, just a spare part.
3
Posted on 4/9/24 at 5:34 am to Scoob
Maybe contact School of the American Rifle. His name is Chad I believe, and he runs an excellent YouTube channel on spec/ tolerance checking AR15 rifles.
Ask him if he’s seen anything like that before, see if he wants the BCG for a video. If you’re gonna trash it anyway, might as well educate others about the issue. Send him some pics.
Ask him if he’s seen anything like that before, see if he wants the BCG for a video. If you’re gonna trash it anyway, might as well educate others about the issue. Send him some pics.
Posted on 4/9/24 at 6:57 am to Scoob
Due to the shape of the bolt carrier, I don’t think there’s any way it could be bent or bowed. It’s more likely it was machined incorrectly, and then the misshapen product got past quality control.
Posted on 4/9/24 at 8:21 am to Squirrelmeister
quote:
Due to the shape of the bolt carrier, I don’t think there’s any way it could be bent or bowed.
I actually watched a youtube video the other day about the different coating options for a BCG and the gunsmith was showing one and said it was actually a damaged bolt carrier he happened to have. Same issue as the OP. Bent ever so slightly. Couldn't easily tell, but it wouldn't fit in the receiver. This was a used one though, not new out of the box.
Posted on 4/9/24 at 12:09 pm to Jon A thon
quote:I can't imagine physical/mechanical stress doing it, not in a rifle. And again, it was bought new and was sitting in it's little bag waiting to be used.
Due to the shape of the bolt carrier, I don’t think there’s any way it could be bent or bowed.
quote:About the only idea I can come up with- are these heat-tempered? Is there any way that process could somehow cause a bow?
I actually watched a youtube video the other day about the different coating options for a BCG and the gunsmith was showing one and said it was actually a damaged bolt carrier he happened to have. Same issue as the OP. Bent ever so slightly. Couldn't easily tell, but it wouldn't fit in the receiver. This was a used one though, not new out of the box.
It's not bent, it's got a slight curve in it.
Posted on 4/9/24 at 3:18 pm to Scoob
quote:
I got it from Primary Arms, but well outside of the return window (I found the order from last September). I sent them an email explaining the issue, but I don't expect anything this late.
There should still be a warranty window to work with.
Funny story- I found myself in Houston a few years ago with an empty afternoon. Had ordered plenty from Primary and figured I'd go check the place out in person. About a 45 minute drive but I'm picturing the Bass Pro of AR15 shops in my head. Finally get there and it is like a 50,000 sq ft warehouse with a 200 sq foot "showroom". It was literally just a little room where you could do pickups for stuff you ordered. And randomly they had a few dummy lowers with triggers you could try and that was it.
If you are bored in Houston, go to Collectors, not Primary.
This post was edited on 4/9/24 at 3:39 pm
Posted on 4/10/24 at 8:18 am to Scoob
quote:
About the only idea I can come up with- are these heat-tempered? Is there any way that process could somehow cause a bow?
There are a few different steels used in bolt carriers but they're all heat treated. And yes, doing that improperly is almost certainly what caused the bow.
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