Purchased a pro hunter two months ago. I tried several bullets with loose T-7 with fair results. Weather was very hot. Today I shot Three T-7 pellets with a 200 gr shockwave on top of a mag sub base . 100 yd groups were approx 2.5". 200 yd groups were poor.
I had noticed when you tighned the front bolt on the forarm down tight you could not insert or remove the ram rod, so I kept this screw a little loose. When I removed the ram rod and tighned the screw down thight, 100 yd groups touched ! and 200 yd groups were 2.5 " with a 2" drop from 100 to 200 yds .Aparently the screw is a touch to long. I put a washer on the for arm bolt to remedy this problem. The sub bases also helped alot . Give this a try if accury is not what you expect