Don't know, but you would need at least one of two measurements to get an idea. One would be the velocity of the bullet, the other would be the point of impact along a distance at at least two additional points.
Over on the "other site" Twanger has a very very accurate graph for velocity vs grainweights of powder that is damn near spot on in real life.
You can find that in my newsletter too.. the third one I think.. at our website;
www.sunrisearchery.com . open the site, go down to newsletters and pick the latest one for twangers information.
If all else fails, I'd use about .240 as a max.
Aloha...
