I wonder what Gary's ball size was for his theory of 71%?
71% load in my .69 does 1,780fps, not 2,000fps, 220fps short of his guess(I assume). Man- did THAT kick - 340gr.2F- AND with a .030" patch with .682" ball - ie: tight. .742- .710" = .032 compression in the bottoms of the grooves = .016 compression in every groove. Yes- I would like it to shoot with a thinner patch, ie: .022 or so - might have found it now, a close weave, thin canvas.
On the other hand, my .45, shooting a 132gr. round ball with 85gr. 2F, delivered 2,270fps, somewhat over Gary's formula and was still 8.72gr. short of 71%, although 270fps faster than 2,000fps.
Using 3F, this speed 2,270fps was duplicated with just 75gr., a full 18.72gr. under his load & still 270fps faster. How thick a patch did he use in relation to the ball also used. The smaller ball or
thinner patch will definitely produce less speed than a tight load. That in itself, is logical.
I sincerely wish these black powder digest writers had done more investigative work, than writing simply what came into their minds. Now, I fully suspect that Gary had a certain gun that developed
2,000fps with a 71%/ball weight load, but suggesting that that formula works for all calibres, especially the big ones, suggests he was merely looking to be paid by the word.
I am also sure that Sam got higher speeds when he put wasp-nest between the powder and his thinly leaky patched ball, mistakenly thinking EVERYONE loaded the same as he did.