+1 on switching up powders and powder charges. I have a ML that when I first bought it shot 6 - 8" "groups" (if you can call them that) with T7 pellets. I switched to T7 FFG loose and immediately the groups shrunk to about 4". Switched to T7 FFFG loose and played around with the powder charges, and now it shoots 1.5". Some rifles just don't like a certain powder or a certain charge- you need to experiment more before you junk it....