By accident, I recently acquired a 22-6mm. ,The gun was sold to me as a 22-250 and I ended up keeping it.) It is a 1:10 twist, very heavy,23#) benchrest rifle with non-taped 27" 1.25" diameter barrel. I'd like shoot 68-70g bullets in it and have several different types on order. I'd prefer to use powder along the lines of AA2700, H-4831SC, or WC-860 as I use these powders for other cartridges which I reload. Any starting load suggestions would be appreciated. I primarily want to work up a load to shoot at prairie dogs at long range.