rsrocket1
Member
I have difficulty accepting the light load theory. My full house 44 magnums loaded with 2400 are the dirtiest cases I ever have. I have never contemplated a cause, I just tumble them and go again.
2400 is one of the slowest handgun powders around. The case still cannot expand fast enough to seal the gases with such a slow burning powder. Try a powder puff load of 6g Clays or Red Dot and I'll bet your cases will be shiny.
In a revolver, blowby isn't much of a problem. In a semi auto, blowby often results in a blast back into your face and possibly burning powder flying back too.
Some powders have a slow initial rise in pressure. Even at max loads, you might end up with a "scorch mark" that only covers part of the case. For me, Titegroup is notorious for this. In the end, it doesn't matter, the case does seal the gases before blowby and the soot all comes off in the tumbler.