Out-Of-Round .45 ACP Casings
BY Herschel Smith
5 years, 9 months ago
Recall I said I had some range time, including with the CMMG PSB .45 ACP?
I kept some of the brass and noticed something for the second time I shot this particular firearm. Some of the brass has burn marks down one side, like this.
That brass is Federal .45 ACP. Some of the brass is clean and well-rounded.
That brass is from Double Tap 450 SMC.
Other .45 ACP ammunition I shot didn’t have the burn mark. I looked more closely at the Federal brass, and noticed what I think is ovality, even to the naked eye.
Given that some brands of .45 ACP can be shot in this gun (along with 450 SMC) with clean results (I also shot a good bit of Freedom Munitions .45 ACP with clean results), I’ve concluded some manufacturers are selling brass that is slightly out-of-round.
I think this is interesting, and I thought I would pass it on.
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On March 1, 2019 at 1:56 am, Nosmo said:
Redding makes a pass-through base sizing die for 40 caliber that seems to very successfully resolve bulged cases in 40 and 10MM. I’d guess it also does a good job at fixing any out-of-roundness. It’s the G-Rx Push Through Base Sizing Die. Their online catalog has a pretty picture of it but no info about what other calibers it may be available in.
On March 1, 2019 at 5:38 am, Marshall said:
Herschel,
Did the rounds feel like they were normal power? Underpowered rounds can have smut on the outside when there is not enough internal pressure to seal the case against the chamber. I have occasionally seen it in some of my test rounds that I intentionally underloaded for quiet subsonic use.
Marshall
On March 1, 2019 at 8:28 am, Frank Clarke said:
I was wondering the same as Marshall, but from the other end of the telescope: if gas is escaping other than down the barrel, that gas is not pushing the round.
On March 1, 2019 at 9:35 am, BRVTVS said:
Cowboy action shooters report this problem with 45 colt rifles. The brass is too strong to seal the chamber with a light load, so blow-by occurs, making for a messy cleanup if black powder is used. The cure (I’ve read) in that case is to shoot heavier loads, anneal the brass better, or switch to a 44-40 rifle.
On March 1, 2019 at 9:53 am, revjen45 said:
Did you measure any of the suspect brass? How much out of round is it?
On March 1, 2019 at 7:30 pm, Gryphon said:
Hard to think “Out-of-Round Cases” is the problem here, as the Bullet would have to also be Irregular in Diameter… in either situation, given Normal Chamber-to-Cartridge Tolerances (Go/No-Go) that are just a few Thousandths of an Inch, a Cartridge Misshapen far enough to allow Blow-By this Severe would likely have Chambering/Extraction Issues also.
I’m going with what Marshall and BRVTVS suggest, Too Low of Chamber Pressure to Seal the Gas. Excessively Hard Brass might cause this, but what I saw when Reloading 9-MM many Years ago was Cases that were not Annealed after the Second Firing would be so Hard they would Split, sometimes even when Setting a Bullet.
If you have any Unfired Rounds from the same Lot, grab a Micrometer and Measure them at 90-Degree Intervals, see what you find.
On March 9, 2019 at 6:39 pm, TRX said:
Any updates on the out-of-round brass problem?
On March 10, 2019 at 1:58 am, BRVTVS said:
A video about similar issues: https://www.youtube.com/watch?v=m0fPrcs6ZC4