I've owned several of these rifles and presently have four;one is on its second barrel, the first having expired after over 3000 rounds(have no idea how many were fired before I got it).Either 60-H4831 or 60 RL22 with 130 Sierra flat base,or 130 Nosler Partitions have done the bulk of the work for me over the years.I've found that if a M70 does not digest either of these loads, it's a sick M70.
I have never had a pre 64 M70 270(FW or Standard) that did not give fine accuracy and good field service with either of these loads.
