OK, not strictly a cast boolit question, but there is more knowledge on this sight than anywhere I know.
My BIL is playing with a 300 BO 7" barrel pistol. He has a lot of old 147 gr military pull downs along with a Lee 150 gr mold. His goal is to find an extremely quiet load for both bullets. Not really concerned if it works the action or not, just looking for a quiet and accurate back yard load (very rural- back yard about 300yds long). I suggested 5.0 grs of Unique, thinking 38 special, 150 gr lswc , approx 900 fps. Didn't work. Got an obvious more than sonic 'crack' when fired with the 147 gr fmj. Why would the 30 BO with 7" barrel produce that much more velocity than my 38 special with 6.5" barrel? I understand that pressures / velocities between the 35 vs 30 caliber will be different, but that much difference surprised me. Also, any suggestions on a load that would acheive what he is trying to do?
Just so you know, we have both been reloading and casting for over 45 years. Probably 50 or more calibers between the 2 of us. Everything from 22 Jet to 45-70. He was a competition shooter for years - long range rifle to bullseye.