Ar Feed Problems

Double J · November 13, 2008, 07:58 PM

What causes an AR 15 not want to feed last two rounds of every magazine?
Started with Brown Bear 62 grain SP
Tried LC military stuff.
Tried Winchester 55 grain SP.
Tried several different magazines.
Cleaned and re-cleaned.
Same problem. 28 out of 30 work fine. Last two won't pick up.

Bruce H. · November 13, 2008, 08:12 PM

Does the bolt stay open like when a magazine is empty, or does the bolt close, without feeding the next to last round into the chamber?

**4V50 Gary** · November 13, 2008, 08:28 PM

Load those magazines with 3-5 rounds and then try them in someone else's AR. See if the problem reoccurs. If they don't, then the magazines are fine. Also, try your ammunition in someone else's gun (if they let you). Same exercise but with 3-5 rounds. You want to preclude the ammunition as the cause.

Check your buffer spring or even the buffer weight. I wonder if it's too strong and slams the bolt back faster than the magazine spring can push a fresh cartridge up? Essentially, I'm talking about hyper-function where the bolt moves faster than it should be. Weak magazine springs can also be the source (that's why you test it in another person's gun).

kraigwy · November 14, 2008, 10:46 AM

First thing I learned when I picked up my first AR (M16A1) when I attended a live fire FTX with pop up shoot back targets, in SE Asia is you neve fully load a M16 mag. you put 18 in a 20 rounder, and 28 in a 30 rounder.

I still shoot ARs, in compitition and plinking. I found the same thing, 18 in 20 and 28 in 30s.

Thats probley where most of the jaming rumers on the ARs come from.

Its a situation we learn to live with.

rocket12 · November 14, 2008, 11:11 AM

the op said LAST two...not FIRST two, big difference, I would suspect weak mag springs

Double J · November 14, 2008, 01:50 PM

OK guys, I think I found what's going on. This rifle has a new Accu-Wedge. The top portion was extending above the lower reciever just enough to get between the bolt and buffer causing friction and slowing the bolt.
On the last two rounds, a weaker mag spring combined with the slower bolt just wouldn't pick up those last couple rounds. I trimmed 3/16 in. off the Accu-Wedge and all goes well now. I've short-loaded and fired several mags now without a hitch.
I've a couple other AR's that also have new wedges in them that I'll check and trim if it looks to be a common problem.
Sometimes when I get really flustered, it's best for me to stop and think it out latter. Thanks for the info. The thought about the stiff springs got me to looking in the right direction.

hodaka · November 14, 2008, 06:41 PM

Good. I think the Accuwedge is designed for a problem that doesn't exist.

**4V50 Gary** · November 14, 2008, 08:12 PM

Success.

November 13, 2008, 07:58 PM	#1
Double J Senior Member Join Date: February 12, 2007 Location: So. Illinois Posts: 547	Ar Feed Problems What causes an AR 15 not want to feed last two rounds of every magazine? Started with Brown Bear 62 grain SP Tried LC military stuff. Tried Winchester 55 grain SP. Tried several different magazines. Cleaned and re-cleaned. Same problem. 28 out of 30 work fine. Last two won't pick up.

November 13, 2008, 08:28 PM	#3
4V50 Gary Staff Join Date: November 2, 1998 Location: Colorado Posts: 21,833	Load those magazines with 3-5 rounds and then try them in someone else's AR. See if the problem reoccurs. If they don't, then the magazines are fine. Also, try your ammunition in someone else's gun (if they let you). Same exercise but with 3-5 rounds. You want to preclude the ammunition as the cause. Check your buffer spring or even the buffer weight. I wonder if it's too strong and slams the bolt back faster than the magazine spring can push a fresh cartridge up? Essentially, I'm talking about hyper-function where the bolt moves faster than it should be. Weak magazine springs can also be the source (that's why you test it in another person's gun). __________________ Vigilantibus et non dormientibus jura subveniunt. *Molon Labe!*

November 14, 2008, 10:46 AM	#4
kraigwy Senior Member Join Date: June 16, 2008 Location: Wyoming Posts: 11,061	First thing I learned when I picked up my first AR (M16A1) when I attended a live fire FTX with pop up shoot back targets, in SE Asia is you neve fully load a M16 mag. you put 18 in a 20 rounder, and 28 in a 30 rounder. I still shoot ARs, in compitition and plinking. I found the same thing, 18 in 20 and 28 in 30s. Thats probley where most of the jaming rumers on the ARs come from. Its a situation we learn to live with. __________________ Kraig Stuart CPT USAR Ret USAMU Sniper School Distinguished Rifle Badge 1071

November 14, 2008, 01:50 PM	#6
Double J Senior Member Join Date: February 12, 2007 Location: So. Illinois Posts: 547	AR Feed Problems OK guys, I think I found what's going on. This rifle has a new Accu-Wedge. The top portion was extending above the lower reciever just enough to get between the bolt and buffer causing friction and slowing the bolt. On the last two rounds, a weaker mag spring combined with the slower bolt just wouldn't pick up those last couple rounds. I trimmed 3/16 in. off the Accu-Wedge and all goes well now. I've short-loaded and fired several mags now without a hitch. I've a couple other AR's that also have new wedges in them that I'll check and trim if it looks to be a common problem. Sometimes when I get really flustered, it's best for me to stop and think it out latter. Thanks for the info. The thought about the stiff springs got me to looking in the right direction.

November 14, 2008, 08:12 PM	#8
4V50 Gary Staff Join Date: November 2, 1998 Location: Colorado Posts: 21,833	Success. __________________ Vigilantibus et non dormientibus jura subveniunt. *Molon Labe!*

November 13, 2008, 08:12 PM	#2
Bruce H. Member Join Date: January 18, 2008 Posts: 22	Does the bolt stay open like when a magazine is empty, or does the bolt close, without feeding the next to last round into the chamber?

November 14, 2008, 11:11 AM	#5
rocket12 Senior Member Join Date: November 20, 2005 Location: ohio Posts: 148	the op said LAST two...not FIRST two, big difference, I would suspect weak mag springs

November 14, 2008, 06:41 PM	#7
hodaka Senior Member Join Date: April 23, 2006 Location: South Texas Posts: 2,010	Good. I think the Accuwedge is designed for a problem that doesn't exist.