Re velocity, forward allowance, flight time, etc: It is indeed true that faster loads slow down quicker than slower loads. But as far as difference in forward allowance goes, it's still going to be greater at longer range than at closer range--for the simple reason that while the velocity advantage of the faster load over the slower load is reduced, the faster load will always retain some velocity advantage.
For example, let's take two 12ga, 1 1/8 oz lead target loads. MV of the fast one is 1400 fps; the slow one, 1100 fps. At 20 yards, fast load velocity is 951 fps; slow load, 790 fps. Flight time to 20 yards is .0511 seconds for the fast load; .0630 for the slow load. At 40 yards, velocities are 679 fps vs 574 fps. Flight time, fast vs slow: .1265 seconds vs .1529 seconds. (Source: John Taylor's "Shotshells and Ballistics".) Which means, even though the difference in velocity between fast and slow loads has been reduced, you need more forward allowance to compensate at 40 yards than you do at 20 yards.
The area in which the slow load does a much better job of "catching up" to the fast load is not in flight time, nor is it in forward allowance (the gap actually widening in both cases) but rather in retained energy (striking/killing power)--because that's based strictly on retained velocity, and that's the area in which slower loads don't give up all that much to faster ones.
Last edited by L. Brown; 03/21/12 08:26 AM.
