I built a 500NE 3 1/4 on a New England (HR) with a 1 in 14 50BMG barrel & it will not stabilize 750Gr's , I dont think I can drive them fast enought AND stay alive LoL

570Gr's are a 1 shot head ache , I now use a 535Gr a 2200fps or so , more like a hot 500BPE or 50/140 , I might use it here in Tassie at the big bore shoot ?