I have always used Hornaday or Sierra 170 grain flat points for 30 30. I have always loaded them the same,win 748 just a touch under max listed in Lyman #48. Lyman lists velocity at 2167 fps. I do not have a chronograph but my best S.W.A.G. is they they are running about 2000fps out of a 20 inch barrel. Recently I came upon a real bargain on four boxes of Speer 130 grain flat points the only data I had was in my Speer # 13 using H322. I loaded a few at just about the middle of the listed range, at 50 yards they are about 6 inches high. So here is my question. Is there a formula using weight, distance, and velocity to calculate how the 130 grain bullet could be loaded to approximate the point of impact of the 170 grain bullets. Sorry I rambled on so,I feel like I didn't express my question very well. Any help would be appreciated.
