Standard 115g Winchester and 90g Winchester Superclean (147g Winchester WinClean looks the same but is more accurate). My brass has always been “dirty” in the 9mm AR using regular 115g or 124g. The rifle is a Colt 6450, 22 years old, all original parts but less than 10000 rounds. My guess is about 6000, most of that mine the last 5 years. Prior to that it sat in a safe at my brother’s, who purchased it new and rarely shot it.
Is this degree of burn normal for the 9mm blowback platform? Note the one split case… It’s been suggested I go with a a) longer spring such as one from a .308 and/or b) restrict buffer travel with quarters or spacer and/or c) heavier buffer (I THINK my stock buffer weight is 5.5oz but I can’t seem to find a reference to verify that).
Looks normal to me, my brass looks a lot worse than that but I’m shooting with a suppressor too. It’s that dirty when I shoot without the suppressor on. " Not something I do often" 8.5 barrel or 5.5 one. Blowback action, if I’m not mistaken there is or was a few blowback guns that did not even have extractors and just used the “blowback” to force expended cases out. Your brass looks even better than brass from a G3 rifles.
The 3 here are from mine after being thrown in a bag of mixed brass and knocking off a bunch of the gunk on them
I shoot suppressed only and my brass is no where near as dirty (PSA 10.5" barrel, 147gr factory ammo). In the MDS thread I linked to a page where the guy talked about buffer weights. 5.5oz is too light as evidence that using a 10oz buffer still operates for me, unsuppressed. That was from this thread:
There is discussion about heavier springs adding to carrier velocity to close the bolt and possible dipping of the muzzle. Don’t know, never tried it. But the same article says the increased spring will not hold the bolt closed longer.
For sure, you want to limit the bolt travel. Use quarters or buy the rubber plug for a few bucks.
I have a pile of 9mm brass (American Eagle 147gr and Lawman 147gr) at home and can post pics tonight.
The degree of dirt on the brass appears to be normal. Brass from ammunition fired in my CMMG 9mm carbine appears a lot dirtier than brass from the same ammunition fired in my pistols.
Split brass is not a normal condition, unless it is brass that has been reloaded several times.
Here’s 5 different 9mm loads (left to right):
Winchester 115g, Winchester 124g NATO, Speer Lawman 124g, Winchester 90g Super Clean, Winchester 147g WinClean. The first 3 are dirty as hell, the “clean” burns nice.
All are accurate at 25yds with 1" groups using a Vortex Strikefire II on top of the carry handle (and cleanly cowitnessed with the A1 rear peep sight). At 50 yards, I found the 147g the most accurate, say 2" groups and a stray or two, the others were more 3-5" (90g the worst at 50).
For kicks, I started stacking quarters, from .50 to 1.75, ALL caused failure to eject/feed issues. Standard buffer and spring are still holding their own, and the bolt catch (knock on wood) still true. Again, recoil not quite to my liking since this is going to be my PCC backup gun once my brand new 6951 gets fixed…
All magazines today were 32 and 20 round original Colt (22yo) magazines and one new 32rd, and one 20rd Metalform. All good.
I’ll be shooting the 147g WinClean in competition…
I’ve found the 124g Federal FMJ to be the most accurate in my carbine, consistently shooting sub 4" groups at 100 yards. I’ve fired quite a few 2-1/2" groups at 100 yards with the 124g Federal.
Winchester 115g shoots 6"-7" groups at 100 yards. Sometimes the groups run 8"-9".
My eyesight is not that great these days. I used an Aimpoint ML2 with 4 MOA dot and held the top of the dot on the center of a light blue B-27 to zero and shoot groups.
For all my blowback 9mms including a RRA & PSA AR, dirty casings are normal.
Stock Colt buffer is 5 to 5.5 oz, which is fine for std. 9mm loads. Hotter & +P loads may benefit from a heavier buffer but you’d probably have to upgrade to a ‘dedicated length’ buffer which is longer and does the same job as a spacer. Either a spacer or a longer buffer won’t affect how soon the bolt starts to open, but helps with taking stress off your bolt catch. Colt 9mm ARs use a long finger bolt catch for last round hold open and are more prone to breaking than std. 5.56 bolt catches.
if your cases show any signs of bulging that’s when it’s time to take action, either with a heavier buffer or stronger spring.
