AR-15 failing to go into battery

[dlbleak]

^^^^Ive had this issue on a completely dry guns. A little mobile 1 on all mating surfaces and drop on the pins for the hammer and trigger solved the problem

 

[leemozoid]

I have a newly built AR-15 pistol with side charger with me at the range, and I’m having an issue with it. If I insert a loaded aluminum USGI magazine into the AR and hit the bolt release, the bolt will strip a round and chamber it, but the bolt itself will not go fully into battery. If I remove the magazine and pull back on the charging handle and release it, the bolt goes fully into battery and will fire normally. I tried a known good bolt from another AR, and experienced the same issue. I also tried another, known good magazine, and still had the same issue. If I load two rounds into a magazine and charge the AR, I have the battery issue, and if I remove the magazine and charge the AR again, the bolt chambers fine. When I reinsert the magazine with one round in it, and fire the AR, the bolt ejects the spent round and chambers the next round but will not go fully into battery. Two different bolts and two different magazines, all of which work just fine in my other AR.

What do you folks think could be the issue with the new AR?

You have two potential problems.

Depending on the length of your barrel, you may have an insufficient gas impulse needed to drive your bolt fully rearward. I would suggest doing some swaps with different springs and buffer weights.

Secondly but less likely you have a dirty chamber. I would still give it a good cleaning/polishing just to make sure there are no issues there.

 

[leemozoid]

Thanks for the responses, folks. I did take several springs and buffers with the idea of trying different ones, but the one-piece spring/buffer that I’d installed wouldn’t come out, so I’ll need to take apart the lower to extract it. No time today, though. I’ll try the suggestion of a known good lower, too. I don’t have any headspace gauges, but should it come to that, I’ll pick up one.

JP Silent Capture?

 

[Perplexed]

JP Silent Capture?

Yep, that’s the one. Heavy buffer IIRC.

 

[Perplexed]

You have two potential problems.

Depending on the length of your barrel, you may have an insufficient gas impulse needed to drive your bolt fully rearward. I would suggest doing some swaps with different springs and buffer weights.

Secondly but less likely you have a dirty chamber. I would still give it a good cleaning/polishing just to make sure there are no issues there.

The problem occurs when I load a magazine and then hit the bolt release. It fails to go fully into battery, even with repeated use of the charging handle. But if I drop the mag with the round still in the chamber and then use the charging handle again, the bolt goes fully into battery.

 

[Snattlerake]

Isn't this why the forward assist was invented?

 

[Perplexed]

Isn't this why the forward assist was invented?

But if I have to use it every single time…

 

[HiredHand]

Back to what Swamprat mentioned… how difficult it it to seat a fully loaded magazine with the bolt carrier forward? I’m thinking it’s a combination of tolerance stacking with the parts you used.

 

[HiredHand]

Isn't this why the forward assist was invented?

The original AR pattern had no forward assist. It was only because some Army officer wanted something beat against that the forward assist was added.

 

[LesEldre]

Factory ammo or reloads? If reloads it could be the bullets not seated deep enough.