Recently, in the last year or so, I tried RX-7. I don't know what the velocity is (no chrono) but the groups have tightened up considerably. I used 25.5 grains as a fireform load under a Sierra 125 SPT and had 5 shots nearly touching at 30 yards. Much better than anything I could do with 4227 or 2400. This is not a max load in my 14" barrel but start lower and work up to make sure the pressure doesn't spike in your barrel. Dan Bowers, on here, has a lot of experience with this round in his 10" barrel and can give better input than I. Hope this helps.

John