Re: AR10 T Load Development to 1000 yards? 20" AR10, 17-4 SS barrel. 175SMK, RE15, begin at 42gr and work up to a chrono'd 2,600 fps, better at 2,610 if you can stabilize a nominal +-8 SD. You'll stay supersonic at 1,000 and if you and the rifle are capable, you'll hit it.