fps variations vs accuracy

[davsco]

was just wondering, if one brand of ammo chrono's at 2700 with extreme spread of 80fps and sd of 20fps, in terms of MOA at 100yds, how would accuracy compare with ammo (let's say same bullet) also averaging 2700 with extreme spread of 100fps and sd of 30fps?

 

[morganlamprecht]

chrono numbers and 100 yd groups dont particularly jive in any sort relevance...you can shoot ragged holes with bad numbers and shoot terrible groups with great numbers...ive got targets at home that are 2-4 grain charge spreads while testing for velocity/pressure that are still ragged hole groups, but because of the difference in charges the string has an ES of 100+

the numbers come into play more and more as the distance increases

 

[HairyDemon]

I think easiest way to tell would be to plug your numbers into your favorite ballistics app and see the differences and you get further out. I can say that in the few matches I have shot I had really solid ragged one hole performing rifle but once I got to the long range stages 800, 900, 1k yd line and that SD/ES started to catch up with me this was the one place I started to have to mess with the elevation knob a click here or there. Could have been because the shorter shots were normally from more improvised shooting possitions so it was me shooting shitty enough to not tell my elevation misses vs otherwise, when we shot at 800+ it was all prone. Good luck hope this helps.

 

[Lowlight]

This does not show up at 100 yards, but more so at 1000 yards...

To explain this, if you look at Coriolis, with the work Hornady did on Ground Effects, they found CE was about equal to a 15fps SD at 1500 yards.

The variation is what gives you the vertical spread at distance

 

[LastShot300]

Frank's test on how recoil management affects SD is worth reading. That alone could easily account for over 20fps in SD.