Been using R15 74 grains, 270gr TSX Great accuracy, but It gives me a sticky bolt all the way back to 69 grains the cases show good.
Shot a couple boxes of the new hornady 270 grain superformance and they chambered great and were as accurate, took one apart and there is 80 grains of a powder I wish I knew what it was. They are 125 fps quicker than the R15 load.
Read a load on H4350 and they show 78-83 grains and 100 fps slower, havn't tryed it personally.
It also appears that they will have to be crimped unless there is another trick, put three in the chamber shot a group and all 3 decreased in total length twice.
Going after a brownie in september, this is serious business
Thanks for any imput!