It's foreign made ammo with the dirtier powders, I'm sure. In a suppressed 300 blk out, it gets a weapon dirty much quicker anyway. When you run the cheap foreign ammo with dirty powders, it gets dirtier that much quicker. I get emails and adds all the time from companies importing powder for 1/2 the cost of IMR, Hodgdon, and Alliant powders. I won't do it. You get what you pay for a lot of the times.