Eh! BCRider, I would say you have earned your five minutes of fame!BCRider wrote:OK, I just went and put proper 3fg black powder into a .357 casing and after tapping it once to settle the powder I kicked out enough off the top to produce the 1/8 inch clearance. The weight of the proper black powder in the casing filled to that level was 23.8gns. So call it 24gns.
I've got a few Lee Dippers so I poured the powder into a 1.6cc and just about filled it. So likely I'm looking at 1.5cc's or a hair
Now given the 1.5'ish CC volume I can't see the extra 28gns of lead taking up a .5cc worth of room. So I'm thinking that you need to run more powder or some sort of filler to be sure you're not leaving an airgap.
And you're 100% right that there is simply no way to overcharge a straight wall casing of ANY handgun round. .45Colt is the largest of the old original calibers and it's sized to take the full case of BP. And let's not forget that .38Spl was originally intended as a black powder round. I don't know if much or any were sold loaded with BP but it was during that cross over time. And for .357 we're only looking at another very few grains of powder courtesy of that extra 0.10 length.
We could even load black or Pyrodex into things like .460S&W Mag or .454 Casull or even the trash bin size .500S&W cases and never even come within 1/3 of the peak pressure such guns are designed to withstand. And in fact they would be "mouse fart" loads from such firearms.
But with anything more than a minimal air gap we start seeing the pressures climb FAST. I would not want to be holding onto the 45-70 rifle that "only" has 35 grains of BP or Pyrodex in the casing and no filler. We're likely talking pipe bomb. And if it didn't split the barrel I'm betting it would be a close thing in some cases. Almost certainly it would be the end of a Springfield Trapdoor given that they aren't tolerant of higher pressures.
Obviously it would be hard to frag a .357 with the smaller charge even if there is an air gap. But good practices start with the small stuff, eh?
I have edited some out for reason of space, but your third comment that I left for this reply regarding your suspicion is mine own as well. I think the idea of simply measuring the bullet, amount that is inserted, minus 1/8-3/16", pour, pack, insert the bullet is the way to go. Really appreciate your insight on this. It's still a go for tomorrow, if I can, I'd like to make up another 50 rounds with the increased load and make the comparison, we'll see. Thanks again.