Factory Superformance 80 grain GMX works well out of my 243. About 1" groups, or maybe a little less, off a block of wood. Advertised velocity is 3400 fps, but I didn't clock it.
Same for me. About 1" groups in my model seven, which was as good or better than anything I've tried, including several different factory offerings and several hand load combinations with 80 gr TTSX. I killed several deer with the GMX and was impressed, however I later bought a chronograph and found that these were only shooting about 3010 fps in my 20" barrel. For comparison, I'm getting 3180 with the TTSX and 1 grain under max load of RL 15 with less recoil and muzzle blast, which is important when loading for a 9 yr old.
