I wanted to put my chrono data into a ballistic calculator for my revo handloads to see what the trajectory looks like. Is 0.286 the accepted number for G1, before I put a huge amount of faith in the results? Are these calculators even trustworthy for flat-nosed handgun bullets?
It is probably somewhere from .12-.16 at supersonic speeds. The Lee 158 SWC GC is .11 for supersonic speeds and weighs 165-169 depending on alloy. The BC dramatically jumps below the speed of sound so I would bet .286 is a good number for subsonic speeds.
I'm being pretty gentle on these right now, so subsonic is OK! Someone helped me out with a Quickload calculation that says putting these in .38 brass over 6.1 or 6.5 grains of Longshot would give 21 KPSI and 25 KPSI respectively. (I don't own any .38 Special guns, only .357 Magnum.) The 25 K load gave very low ES/SD at around 1020 fps. Could be a winner!
But good to know! So, how do you deal with a bullet that drops subsonic halfway to the target?
Last edited by BuckRimfire; 04-07-2022 at 12:54 PM.
Another question (which maybe should have it's own post): Anyone have a subsonic BC for the immense 358627 SWC? I bought some of those and they shoot pretty well at 25 yards.
Originally Posted by BuckRimfire
A bullet has many G1 BCs for different velocity ranges. The G7 BC accounts for BC changing with velocity, but I don't know anybody who has tested every different cast bullet with a doppler to figure that one out.
I really doubt it is .286, that's not uncommon for rifle bullets. .186 would be more likely, and falls inline with what I've seen. If you can't test trajectory, a doplar style chronograph is the only other accurate way I know of to get an accurate BC. If you were really trusting, you could set a normal chronograph at 100 yards, and shoot over it.
The Lyman Cast Bullet Handbook 3 has tables of measured BCs for most of their rifle designs and I think the handgun ones are in their Pistol and Revolver Handbook of similar vintage. As I recall, the BC for the 358429 was quite impressive for a revolver bullet. Sorry, can't get to my copy just now.
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