Today I finally got to do some basic testing. . .
Chronographed Guatemalan M193ED (Extra Discolored) 1993 lot 3 . . .
3115, 3169, 3163, 3167, 3148, 3097
That's from a 16-inch barrel with a silencer, distance 15 feet from my Beta Chrony. There were no unpleasant surprises while shooting this ammo. Everything fired when it was supposed to. The cases showed no evidence of high pressure or hard extraction, the ejection pattern was fine. The only thing I didn't get to check today was accuracy. Despite its battle-scarred appearance, this ammo shows every indication of performing well.
Worth noting: I never experienced any funny smells either before or after firing.
Also worth noting. . . My previous two crates were 1993 lot 1 and lot 3, both with large amounts of corrosion and discoloration. Today UPS brought my replacement crate and picked up the severely corroded stuff I had packed up. The new crate is 1997 lot 7 and the ammo is beautiful. It's so shiny and spotless!