In need of help. Malfunctioning parts gun with XM855

**bloodlord77** · 11-13-16, 17:03

I had a crazy kind of malfunction today. I had fte malfunctions everytime I pulled the trigger on a m855 round. The extractor ripped the edge of the rim off, but the casing was stuck in the chamber. This ar operated flawlessly with multiple mags of m193, yet every round of m855 would get stuck in the chamber. My Colt ran both of these rounds flawlessly during the same session. Do you think this is an out of spec chamber, a weak extractor, or the ammo maybe?

In the pics below, you can see the malfunction. I had m193, and m855 loaded alternately. The m855 is stuck in the chamber with a m193 jammed under it.

20161113_122441.jpg 20161113_122507.jpg

**Ryno12** · 11-13-16, 17:08

Sounds like an ammo issue to me. Try the 855 in another AR. If it happens there too, contact the manufacturer of the ammo.

ETA... Whoops, missed the part about them working in your Colt.

**556BlackRifle** · 11-13-16, 17:13

Since it works in your Colt, I'm leaning towards an out of spec chamber. Who is the manufacturer? Also, hard to see in your pic but is that a flattened primer on the stuck case?

**Eric** · 11-13-16, 17:44

Configuration details would be helpful. With extraction troubles start diagnosis with a freshly scrubbed chamber (chamber brush), inspection of the extractor to be sure the extractor groove is intact and a proper extractor spring w/insert is used, like a Colt, Wolff, BCM. If you're experiencing extraction problems with 5.56 and not .223, the chamber may be cut at or closer to .223 specs. It's interesting that M193 ran okay and the M855 choked, but ran okay in the Colt. If it does not resolve, I would suspect the barrel and would chat with the manufacturer.

**Iraqgunz** · 11-13-16, 17:48

So here's the problem. Said ammo works in another gun with no issues. Different ammo works in this upper with no problems. You could probably help us out buy giving a breakdown on the parts used (barrel, BCG, buffer, etc..).

**ST911** · 11-13-16, 17:55

Originally Posted by bloodlord77

I had a crazy kind of malfunction today. I had fte malfunctions everytime I pulled the trigger on a m855 round. The extractor ripped the edge of the rim off, but the casing was stuck in the chamber. This ar operated flawlessly with multiple mags of m193, yet every round of m855 would get stuck in the chamber. My Colt ran both of these rounds flawlessly during the same session. Do you think this is an out of spec chamber, a weak extractor, or the ammo maybe?

In the pics below, you can see the malfunction. I had m193, and m855 loaded alternately. The m855 is stuck in the chamber with a m193 jammed under it.

Originally Posted by Iraqgunz

So here's the problem. Said ammo works in another gun with no issues. Different ammo works in this upper with no problems. You could probably help us out buy giving a breakdown on the parts used (barrel, BCG, buffer, etc..).

In addition to what IG said...

You are using genuine USGI M193 and M855? Or XM193 and XM855? Or something M193-ish and M855-ish?

**bloodlord77** · 11-13-16, 18:04

Originally Posted by Iraqgunz

So here's the problem. Said ammo works in another gun with no issues. Different ammo works in this upper with no problems. You could probably help us out buy giving a breakdown on the parts used (barrel, BCG, buffer, etc..).

complete bushmaster lower with h buffer and sprinco spring. Bushmaster upper with yhm barrel and bcm carrier and bolt. Didn't know if i should list manufacturers as I haven't contacted anyone about the issue. I was using xm855, and xm193. It is not a flattened primer in the pic, its the rim edge peeled back. Could an excess amount of grease cause the extractor to slip off? When i tapped the casings out with a cleaning rod, they came out rather easily. Thanks for the help.