9mm AR Issues

[M1_Garand]

I took my latest 9mm AR to the range yesterday and kept having doublefeed and stovepipe issues:

My initial thought is to polish the feed ramp and check the extractor - any other items I should check? The build is:

 

CMMG MK9 lower

PSA 10.5 upper & ramped bolt

KAK tube, PSA 9mm buffer weight, milspec carbine buffer spring

CMMG Milspec LPK

Colt style 32 round SMG magazines (unsure of MFG - one is labled "Brownells", the other "Palmetto State Armory.") I was able to repeat the malfunction with both magazines. I was also only loading 5-10 rounds per magazine.

I was using bulk Remington UMC 115gr 9mm FMJ ammo. The ammo was giving my Sig Sauer P938 some extraction issues (the extractor failed to grab 2 out of approximately 100 or so rounds I fired at the same time, my CZ75 SP01 ate all of it without issue) and the Sig will normally eat anything. I can't see the ammo causing the double feed issues, however.

 

Thanks in advance.

 

[R1100R]

Have had numerous issue with the Remington UMC 9.  It will not cycle most of my weapons. The same with Tula Brass Maxx. It seems to by under powered.  I would try some other ammo first. 

Edited November 14, 2016 by R1100R

[hipower]

PMC Bronze, Federal, Sellier&Belloit, etc, I find that the European 9mm seems to work better in the AR9s I have. And 124 grain works very well.

I have had some cycling issues with Freedom Munitions reloads, and Winchester white box ammo. For the most part, my experience has led me to using a hotter load ammo for less problems. Granted I'm not an expert, not even close, but I'd recommend trying some 124 in yours.

[M1_Garand]

Thanks guys. I'll try some hotter ammo before I start tinkering.

[Westwindmike]

Don't know about needing hotter ammo. My AR9 shoots my 124gr RNL reloads at 1000fps with no problems. I think my 32 round mags are Centerline or something like that.

[tmauto769]

mine got a little better when I bent the ejector in a hair, but it still wasn't perfect. Which is why I ended up getting rid of mine, more hassle than it was worth. I will just pick up a cz scorpion when I can.

[hipower]

2 hours ago, tmauto769 said:

I will just pick up a cz scorpion when I can.

Now you're on the right track!! I love mine!

But back on the AR9 topic, the only issue I've had with a PSA model has been with Freedom Munitions ammo.

[Dolomite_supafly]

You can tune 9mm's just like you can 5.56's. You can use buffers of different weights to tune them to your liking. My 9mm AR with a ~3.5" barrel has a very heavy buffer because I want it to be as quiet as possible with a silencer sometimes it has a malfunction but it is pretty quiet. My wife's 9mm AR has a light buffer so it will be reliable.

[chuckstur]

On ‎11‎/‎14‎/‎2016 at 9:56 AM, M1_Garand said:

I took my latest 9mm AR to the range yesterday and kept having doublefeed and stovepipe issues:

My initial thought is to polish the feed ramp and check the extractor - any other items I should check? The build is:

 

CMMG MK9 lower

PSA 10.5 upper & ramped bolt

KAK tube, PSA 9mm buffer weight, milspec carbine buffer spring

CMMG Milspec LPK

Colt style 32 round SMG magazines (unsure of MFG - one is labled "Brownells", the other "Palmetto State Armory.") I was able to repeat the malfunction with both magazines. I was also only loading 5-10 rounds per magazine.

I was using bulk Remington UMC 115gr 9mm FMJ ammo. The ammo was giving my Sig Sauer P938 some extraction issues (the extractor failed to grab 2 out of approximately 100 or so rounds I fired at the same time, my CZ75 SP01 ate all of it without issue) and the Sig will normally eat anything. I can't see the ammo causing the double feed issues, however.

 

Thanks in advance.

 

Looks to me like the round did not get under the extractor.  Make sure it has a slight chamfer.

[trentatron]

I had a similar problem with my 7.62x39 AR pistol, and an overpower extractor spring seemed to fix it. In full disclosure, I had already cut the M4 feed ramps out, and polished it down to one large ramp for the 30 cal round. 

I don't know if that helps at all, but it's cheap, and can't hurt to try if it's not an ammo issue.