martin_b Posted June 13, 2020 Report Share Posted June 13, 2020 I tried to take my M55 .223 out to 600 yeards today at Bisley. According to Strelok my 55g bullet should still have been supersonic (1375 f/s) but I tried 3 times and couldnt get any shots to register on the electronic boards. Strelok was bang on with its vert calc with the .223 @ 300yards and there was very little wind this morning, I did wonder if the scope had moved so checked the rilfe back at the Zero range but it was fine. Was i just unluckly or getting to the point where the bullet could have started tumbling? Quote Link to comment Share on other sites More sharing options...
20series Posted June 13, 2020 Report Share Posted June 13, 2020 What elevation did you have for 600? Quote Link to comment Share on other sites More sharing options...
martin_b Posted June 13, 2020 Author Report Share Posted June 13, 2020 15.1MOA... However I was shooting Magtech 55g cooking ammo and I do wonder if the printed BC of .272 is a trifle optomistic. If it was say .24 then that makes very little difference at 300Y but a big difference at 600y (subsonic @600) Should also say i aimed the last shot deliberately high, so i think the issue was speed rather than aim. Quote Link to comment Share on other sites More sharing options...
20series Posted June 13, 2020 Report Share Posted June 13, 2020 Have you chronographed the ammo Quote Link to comment Share on other sites More sharing options...
KABOOM Posted June 14, 2020 Report Share Posted June 14, 2020 8 hours ago, martin_b said: 15.1MOA... However I was shooting Magtech 55g cooking ammo and I do wonder if the printed BC of .272 is a trifle optomistic. If it was say .24 then that makes very little difference at 300Y but a big difference at 600y (subsonic @600) Should also say i aimed the last shot deliberately high, so i think the issue was speed rather than aim. I think running a few shots over a chronograph is in order. Perhaps MagTech was doing some creative B.C (BS). Perhaps create a range card by shooting at assorted distance recording elevation changes and drop. Best wishes for good shooting. Quote Link to comment Share on other sites More sharing options...
VarmLR Posted June 14, 2020 Report Share Posted June 14, 2020 17 hours ago, martin_b said: I tried to take my M55 .223 out to 600 yeards today at Bisley. According to Strelok my 55g bullet should still have been supersonic (1375 f/s) but I tried 3 times and couldnt get any shots to register on the electronic boards. Strelok was bang on with its vert calc with the .223 @ 300yards and there was very little wind this morning, I did wonder if the scope had moved so checked the rilfe back at the Zero range but it was fine. Was i just unluckly or getting to the point where the bullet could have started tumbling? were you using G1 or G7 form factors in Strelock? Sounds like a G1 BC which won't be accurate over 3 to 400yds. It's the wrong form factor for the bullet. Swap to a G7 and tune the velocity to measured velocity to re-set actual BC and it should sort things out. Quote Link to comment Share on other sites More sharing options...
martin_b Posted June 14, 2020 Author Report Share Posted June 14, 2020 I'll borrow a chrono from my club as soon as I can and get some true speed values.. thanks for the advice Quote Link to comment Share on other sites More sharing options...
MarinePMI Posted June 14, 2020 Report Share Posted June 14, 2020 Interesting. A 55gr Nosler BT is supersonic for me out to 700. And that's with a much crappier BC than .272... Quote Link to comment Share on other sites More sharing options...
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