Originally Posted by
rodwha
What??? BC just is and it certainly means something to a RB even to 50 yds all depending.
My ballistics calculator is set for 900’ elevation for where I am. This is roughly what I estimate 70 grns of 3F T7 to do for a 177 grn .490” patched ball with a zero set at 100 yds with figures for every 25 yds. This gives me an 1830 fps velocity. Granted the low BC value doesn’t negatively effect the drop too much to be concerned about out to 125 yds but it certainly effects the wind drift, which is what was mentioned, even with a light 10 mph 90* crosswind.
With a very light 5 mph crosswind it drifts 0.3”, 1.2”, 2.8”, 5.1”, and 7.9”.
At 10 mph it drifts 0.6”, 2.4”, 5.6”, 10.2”, and 15.9”.
At 15 mph it drifts 0.9”, 3.6”, 8.4”, 15.3”, and 23.8”.
And at 20 mph it drifts 1.2”, 4.8”, 11.2”, 20.3”, and 31.8”.
Pretty drastic when it gets a bit breezy actually. But even at 10 mph, which isn’t real that bad it makes a 100 yd shot a bit questionable. Even a 75 yd shot is a bit much. I can estimate distance we’ll enough but judging wind speed and direction not so well.