There are lots of good 222 Mag powders out there.
748, 335, 2230, BLC-2 will all give top speeds and accuracy with varmint weight bullets and easy metering.
Older stuff like 3031, 4895 and 4064 has always worked. A 1969 IMR manual shows 27.5 grs of 3031 kicking a 50gr Hornady at 3,570 at 50,000psi. I used the same load and hit 3,500.
I happen to like Benchmark the best with 40 or 50gr. bullets.
26.5-27grs. will clock 3,500 in a 23.5 inch barrel with 50 grainers and I run 29 grs. for 3,900 with the 40's.
If looking for newer data/powders to work with, 5.56 NATO data will get you to about the same pressure as the SAAMI .223 Remington, but you still need to work up.
Its not worth a hoot for varmint splatter, but THE most accurate 100yd. load out of 4 222 Mags I've shot (even a fast twisted one) is 27 grs. Benchmark, 53gr Sierra MatchKing, Herter case and a Fed. 205 GM.
