I understand the problems with T7. That's why I don't recommend using it with 209 primers. It's better with #11 caps, but still not great.

I had 7 CVA inlines of every model made. They all shot BH 209 perfect, and were all accurate. I even shot two of them without the BH breech plugs. No slow, or misfires.

I believe the majority can say this same thing about BH and CVA guns.

No idea why you have so many problems.