I have fired my .223 Spacegun at 1000 yds in competition using 80 gr Sierras. I asked the guys in the pits and they assured me the rounds were supersonic going over and got very nice groups (at least for me). I did however pop about half the primers on that load so haven't done it again. That said all I wanted the round to do at 1000 yds was make a hole in paper. If I wanted more than that I would adjust accordingly. (Poking holes in paper is about like breaking glass as far as I can see.) .308 is marginal on staying supersonic as is 30-06 at 1000 as well, I wouldn't risk either my Supematch .308 or M-1 loading for supersonic at 1000 (not wanting to bend op rod). I have considered putting a fore end handstop on my Tikka COntinental .270 as I think I could push that to be well above supersonic at 1000 without concern but the bullet is a bit light. I suppose to really stay powerful at 1000 one really needs to go 300 win mag or above. ANyway, just thinking out loud.
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