MEC charge bars have had holes in the powder bushing bore for a long time. It's difficult to use the machine without a bushing.
The head needs to be tipped back to change powder bottles. No powder should remain in the bushing. Generally, a powder change means a bushing change also. Not always.
Personally, I stick to middle of the road recipes. Nothing real low or real high pressure. I do prefer Alliant powders as I consider them the easiest to ignite of the bunch.
I've suspected for a long time that quality control on primers is not what it should be. That may be the joker in the deck.
