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Posted: 2/27/2012 11:12:32 AM EDT
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I just finished and test fired a 308 build using Mega MA-Ten upper/lower combo, standard AR LPK with DPMS 308 bolt catch, DPMS BCG, 308 carbine buffer and DPMS spring, Magpul ACS stock and Rainier 16" ultra match barrel.
Everything is shooting well, but I'm having an unusual problem. With the bolt locked back and the mag out, bumping or retracting the stock will release the bolt. Has anyone seen this before and identified a fix? I could try a stiffer bolt catch spring (if such a thing exists), a different bolt catch brand/design or maybe a lighter buffer spring with heavier buffer (last resort). Any thoughts? - Dave |
| If it helps, I recently discovered the same thing on a DPMS AR15 that I have. I inquired about it here on the forum and I was told that it's actually normal. Mine happened to happen when I was putting the rifle beside the bed with a full mag. The muzzle was pointed right at my face when it happened. Scared the shit out of me! |
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Quoted:
I just finished and test fired a 308 build using Mega MA-Ten upper/lower combo, standard AR LPK with DPMS 308 bolt catch, DPMS BCG, 308 carbine buffer and DPMS spring, Magpul ACS stock and Rainier 16" ultra match barrel. Everything is shooting well, but I'm having an unusual problem. With the bolt locked back and the mag out, bumping or retracting the stock will release the bolt. Has anyone seen this before and identified a fix? I could try a stiffer bolt catch spring (if such a thing exists), a different bolt catch brand/design or maybe a lighter buffer spring with heavier buffer (last resort). Any thoughts? - Dave It could be that the bolt catch plunger spring is too weak, or the plunger pocket was driilled to deep....check the magazine follower has enough spring tension when empty...also, see if their is any burrs, or dirt trapped in the bolt catch channel. Lastly, add a little lube and see if it helps any...Sometimes their is too much tension from the bolt catch and the magazine spring has a hard time over comming the tension, and thus only makes light contact w/ the bolt...In that case, the plunger spring pocket may have been drilled a little too shallow... Hope this helps, |
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The consensus seems to be that it's normal, though it's a little discomforting when it happens. I guess as long as I expect it, it's not a big deal.
Good thought on how the bolt catch spring well was drilled. I've been thinking I'd need a new spring, but raising that floor a fraction of an inch may have the same effect as a stiffer spring. I'll give that a shot as well as your other ideas. - Dave |
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it is normal and cannot be "fixed". without an empty mag in the weapon there is nothing holding the bolt catch up exept the forward pressure of the
BCG. when you bump the rifle form behind the BCG bounces back on the buffer sprin slightly, the bolt catch drops and the bolt closes. this is the reason you shouild not leave a loaded mag in the weapon with the bolt open as some people do. |
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Quoted:
The consensus seems to be that it's normal, though it's a little discomforting when it happens. I guess as long as I expect it, it's not a big deal. Good thought on how the bolt catch spring well was drilled. I've been thinking I'd need a new spring, but raising that floor a fraction of an inch may have the same effect as a stiffer spring. I'll give that a shot as well as your other ideas. - Dave the bolt catch spring holds the bolt catch DOWN (the position that releases the BCG) it is pushed UP by the follower in the empty mag. |
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Thanks for pointing that out. For some reason I have a mental block that the action of the bolt catch is opposite of how it really is, even though I have no problem using it in practice.
What's puzzling to me is why this doesn't happen frequently on AR-15s as well. The mechanism is essentially the same. The only differences are that the mass of the bolt itself is much less and that a smaller portion of the catch is in contact. - Dave |
| It is normal. It also is a ceremonial procedure during the changing of the guard at the Tomb of the Unknown Soldier with the M14. Using that same butt-slapping technique on the AR achieves the same result. The inertia causes the bolt carrier group to travel rearward, releasing the tension on the bolt catch, which is pushed down by the bolt catch spring and buffer. Same thing happens when the AR is dropped on its butt from even a small height. |
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Quoted:
It is normal. It also is a ceremonial procedure during the changing of the guard at the Tomb of the Unknown Soldier with the M14. Using that same butt-slapping technique on the AR achieves the same result. The inertia causes the bolt carrier group to travel rearward, releasing the tension on the bolt catch, which is pushed down by the bolt catch spring and buffer. Same thing happens when the AR is dropped on its butt from even a small height. yup, what he said. same thing on the AR15 |
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