Lots of loads listed using the various 4350's, go with what you have, nearly 50 years with the 6.5 and I have never found a 'bad' powder.
My thoughts exactly. I got my first 6.5x55 in 1978 (a cherry M94 carbine, one of those I wish I had back) which started a long history with that caliber for me. A string of Swedish Mausers of all flavors and even a couple U.S. commercial jobs (Model 70 and Ruger #1) have blessed me with their presence- but alas no Norwegian Krags. One thing I've found is that this cartridge in general is very forgiving of powders, but I have graduated to the slow suff. IMR-4831 is my current powder of choice, as well as medium weight bullets in the 120-140 weight range. If I couldn't have a .30-06 if limited to "one gun", please let it be a 6.5x55!
