I was going to ask if you tried BH209 with the updated BP, but I noticed the dirty plug in your picture. I also upgraded my BP, but after shooting I don't have that much dirt around it!

Can't remember what plug I bought, but my gun loves BH209 and Hornady XTP sabots.

Sorry pal should have asked what primers you used. that may have been the reason for the dirty BP and not blow back.