Having issues with PMC Bronze

[CarlosDJackal]

Well, I purchased a case of the stuff at the last Gun Show for $355. But since I started shooting it I've had 5 Failures to Extract. I currently have just under 3,000 rounds through my LWRC M6A1 (10.5-inch bbl). But since i was doing a lot of suppressed shooting (all the issues occurred unsuppressed), after the first FTE I thought it was just dirty so I cleaned it prior to doing some test with what was left of my S&B ammo and the next batch of PMC ammo I was took out of the case.

After two more FTEs, I thought the suspect was the S&B ammo since it did so with one o the last ones. But to be sure, I tried Militech Grease as lube of the BCG. Today I shot through 120 rounds of PMC and had 2 more FTEs. I even wiped off the Grease and put in Break-Free Extreme Sports Lube (I have a bottle of Slip 2000 on the way). But after I had another FTE, I looked in the ejection port to see a lot of what is either pieces of the brass or unburnt powder!! And it all came from the last 40-rounds because I had made sure it was clean before putting the BF-ESL in.

Tomorrow or this weekend, I plan on going back out to the range with some UMC or PRVI ammo just to see if I can induce the same malfunctions. I am also going to re-install the original extractor spring just to see if that may be it (I had replaced the spring and insert with a Buffer Technologies "upgrade" kit which included the black donut (black spring insert).

I will update as appropriate.

[Oscar 319]

My Colt 6921 has digested more of this ammo than anything else (55 grn PMC Bronze). I have never had any major malfunction, though the last 6 boxes I bought and ran though it (plus a few Rem and Fed Tactical) last week seemed dirty as hell. I know it is not the cleanest stuff, but it was Wolf dirty w/o the laquer. The 130 rounds looked more like 600.

It was dirty enough to make me reconsider using it. It has never been this bad. Maybe they changed powders? FWIW.......

[CarlosDJackal]

I've shot the stuff before as well and don't remember it being this dirty. In looking inside the firing pin channel of my bolt, it looks more like some sort of coating for the case (maybe that's what they mean by "Bronze"?). It was very fine and somewhat flaky.

I wonder if they changed their manufacturing process so that they added some sort of powdered lube to the case and that's what's getting into my bolt and coating the chamber?

[RogerinTPA]

I've fired a lot of this as well with no issues and shoots pretty tight groups. There are others that have experienced short stroking from being under powered but I haven't. It may be a bad lot of ammo or maybe they changed something in the manufacturing process. Try it in a different AR and see what happens.

[markm]

PMC bronze in another case of import ammo with the WRONG propellant. It will run in most carbean length gas systems from what I've gathered on the gun boards. But it's a little underpowered. And it short strokes like a mother in my rifle length gas systems.

The mild loading isn't an excuse either. There's plenty of mild factory .223 that will run a rifle gas system all day long. I can load my own cream puff ammo that will run better than this stuff. It's just the wrong propellant scenario that seems to be common with a lot of this crappy import ammo we're seeing.

[CarlosDJackal]

Then it looks like the crappy powder may be the cause of the fouling. :mad:

[markm]

Then it looks like the crappy powder may be the cause of the fouling. :mad:

It could be. I didn't notice this stuff being very dirty, but I only fired a few boxes of it.

[MR_X]

about 80% of the ammo used in my M&P15T is PMC. Never had an issue with it beside being extremely dirty and leave brass shavings.

[markm]

about 80% of the ammo used in my M&P15T is PMC. Never had an issue with it beside being extremely dirty and leave brass shavings.

Most carbeans seem to run it fine. Still though... an ammo that won't run in a standard 20 inch gas system is seriously questionable. I have a problem with that. Even if I never intend to use it in a rifle gas system.

I'm the same way with ARs. If an AR won't run commercial .223 and Mil 5.56 ammo, it's not acceptable to me.

[CarlosDJackal]

about 80% of the ammo used in my M&P15T is PMC. Never had an issue with it beside being extremely dirty and leave brass shavings.

This may have been the root cause of the issue. Something "crap" (looked like brass shavings) got stuck in the chamber which required some force to extract the spent cases. It took me quite a bit of work for me to finally clean it out.

I replaced the extractor and made sure the chamber was free of foreign objects and the gun runs fine now. Even with PMC ammo (I only shot a box through to for testing).