AR Not Picking Up Rounds

[etrain16]

Remind me...is this an Anderson lower?

Yes, it is.

 

[Misteramax]

If I recall you had

Yes, it is.

Problem solved. Lmao.

Seriously...they don't check their Mills/fixtures/tool wear.

 

[11Charlie]

It doesn't work even if you slap it real good? What if you don't load the magazine all the way?

 

[etrain16]

If I recall you had

Problem solved. Lmao.

Seriously...they don't check their Mills/fixtures/tool wear.

Okay, so if it's out of spec, is there any possible way to make an adjustment of some kind to make it work a bit better?

 

[etrain16]

It doesn't work even if you slap it real good? What if you don't load the magazine all the way?

The problem only occurs on a closed bolt. Open bolt, fine. Follow up shots, fine. Partially loaded or fully loaded mags don't have any effect. PMAG's vs. metal mags also make no difference. It appears the mags simply won't fully seat on a closed bolt, once they do seat properly, they stay where they're supposed to be and function fine after that.

 

[Misteramax]

Okay, so if it's out of spec, is there any possible way to make an adjustment of some kind to make it work a bit better?

No. That's why it's important to run a mill well with qc checks and scrap parts out of spec.

Your catch location is just slightly out of spec. It's an Anderson. Just buy another one. I don't buy Anderson mfg. Anymore. Had one with the hole location to the mag release button out of spec. Would bind.

Lowers gtg are: spikes, stag, Anderson arms (not mfg from Kentucky, but out of Lebanon or. Coat of arms in Salem has them).

 

[Velzey]

I just had this exact problem but it was on a older Bushmaster. It was a rifle that was purchased new 20 years ago and put away. Last month the owner finally took it out.. Same problems
So after a few hours of measuring I realized two things. The magazine release was sitting on the high side towards the top of the receiver so it's location was .015 higher than normal. And the bushmaster carrier is .025 thicker on the bottom.
This was the perfect combo for short stroking. The bolt assembly was losing velocity because it was rubbing on the top of the magazine. I tried all types of mags. They all rubbed.
Since the carrier is case hardened I just swapped it out and it was up and running.

 

[etrain16]

I just had this exact problem but it was on a older Bushmaster. It was a rifle that was purchased new 20 years ago and put away. Last month the owner finally took it out.. Same problems
So after a few hours of measuring I realized two things. The magazine release was sitting on the high side towards the top of the receiver so it's location was .015 higher than normal. And the bushmaster carrier is .025 thicker on the bottom.
This was the perfect combo for short stroking. The bolt assembly was losing velocity because it was rubbing on the top of the magazine. I tried all types of mags. They all rubbed.
Since the carrier is case hardened I just swapped it out and it was up and running.

Interesting. The one thing I haven't tried yet is to swap this lower with a different upper and see if the problem follows the lower. If it doesn't, then maybe the BC could be part of it too? I'll see if I can get a few moments to try swapping and see what happens.