If you'll recall, I was experimenting with my AR 15 that tended to be a little cranky with steel-cased ammo. Previously, I'd run about 150 rounds through it using a ratio of 1 brass to 10 steel cased rounds and found some success. I finally succeeded in getting back out to the range yesterday to do further testing.
Although I didn't get to shoot as much as I wanted, I still think my results are significant. I put an additional 50 or so rounds through the AR, which operated without a hitch. I still haven't cleaned the gun. Before shooting, I opened it up, and true to the Tula reputation, the insides were quite filthy. Nevertheless, the gun operated reliably and I experienced no malfunctions of any kind in the entire 50 rounds.
For the record, that's nearly 200 rounds of steel cased ammo that I've fired through my gun. Before I started mixing steel and brass, the same gun would malfunction on steel ammo, almost like clockwork, before I could finish the third mag. Usually, the stoppage wasn't fixable without a cleaning rod.
Although my methods are not even close to scientific, they're good enough for me. Yesterday, I also bought a few more boxes of steel cased ammo, which I intend to keep shooting (for cheap).
I'm going to continue this test. I want to run the AR to failure using this dirty, cheap, steel cased ammo, performing no maintenance except for oiling with Mobil 1 synthetic 10W-40, my preferred lubricant of choice. People may laugh at this, but I've had excellent results. The oil stays where I put it...even after many rounds, when I open up my gun, the internals are still thoroughly coated with oil. There's little to no cook-off, even on the back of the bolt where most of the heat and carbon usually build up. And, the anti-deposit nature of synthetic oil means that most of the gunk is actually suspended in the oil, not fused to the metal parts of my gun. It just works.
I figure if it holds up for a 1,000 rounds with dirty Tula, it should be just fine to shoot that much or more of brass without worrying about a significant malfunction.