I just took delivery of mine and havent had a chance to shoot yet. However, gunsmith travis redell broke in barrel and worked off of 45 grains of r-22 75 a-max. test target was in 3's no pressure vel. 3400. same set up 8 twist but broughton.
I wanted to use a Hodgdon Extreme Powder, H4350 looked like it would work, and I have a lot of it. I just didn't want to start from scratch. From what I have read 3400fps seems to be a good accurate vel., any other help is welcome.