RE:
I have an Encore (not a Prohunter) and I went to Blackhorn 209. No crud ring like T7 and you can shoot on the range as many times as you want without cleaning. Just clean it when you get home.
As others have said, try differents loads, but I'm shooting a 300 grain Nosler Partition (.458 cal) in a MMC Orange Sabot. I use 110 grains of BH209 and at 100 yds, it will overlap the bullet holes.