I find my factory pad to work quite well. I never load hot, if I need more power I just move on up in size. You mentioned subsonic, or 1600 fps. In another thread here I posted my load to a gentleman that had a chrony, I do not, and he loaded up some and got terrific results- 1319 fps, with an extermely accurate loan in my gun, with a 440 gr bullet. That load is about like shooting a std 20 ga round. Unless you are trying for artillery class loads, dont worry about it.