There are lots of examples out there where a small amount of setback (increase in case fill percentage) of a 9mm or 40mm round converted a near max load into an over the max load.
Yep, but the 9mm and the .40 are "special cases", in that they are small volume cases already loaded to high pressures, so a very small change in the volume of the powder space has a significant impact on the pressure. This is not the case with may other rounds, particularly rounds like the .38 Special, or any of the larger cased rounds. AND, it also depends on the type and amount of powder being used.
For example, for over a century, the usual .38 Special target load has been a flush seated wadcutter (148gr usually( and somewhere between 2 and 5 grains of a fast powder, and that amount doesn't even fill 1/4 of the volume available in the case.
Personally, I prefer to use powders that fill the case about half-way or more. Not because I'm concerned about the "empty space" but because a double charge is easily, and almost instantly seen.
For bullet length:
But what about that one in the load data. If you do not have one for reference, finding the info is generally not a "just look it up" thing.
The way I look at it, if you don't have one in your hand to measure, you don't have any to load, so how relevant is it, actually??
Primer "brisance"
"Brisance" is one of those terms that has multiple meaning, depending on context. Like "caliber" context determines what is being referred to, more than the common definition.
Look up "brisance" and you'll find it refers to the "shattering force of an explosive" and/or the speed of propagation of the blast wave.
BUT, when you're talking primers, its commonly used to describe the length, duration and "strength" of the flame. Like caliber, which means the size of the bore & projectile in small arms, in artillery and naval "rifles" caliber ALSO means the length of the gun barrel in bore diameters. Context matters.
And for most sources of info on how "hot" a primer is, the focus is on large rifle with little or no info on small pistol.
And you're not likely to find that, for good reason. First point, its a popularity thing, more research and testing goes into area the testers feel their readership is most interested in. And most of the time, that is the high performance end of things.
Second point, look at what you're lighting off. With the biggest volume cases made to use small pistol primers, you're igniting something less than 20gr powder, often only 3/4 of that, or less. With magnum rifle cases you can be lighting off somewhere between 50 and 80 some grains of slow powders. Its not an apples to apples straight comparison.
I run my .357 loads to the full potential of the round, or close to that. Yes, part of that is because I do enjoy the "big boom" but its also so I am practiced and capable with the most "serious" rounds I am going to shoot.
I don't (and won't) have any small guns in .357, and I'm not going to download my rounds to run in them. My current .357s are S&W model 28, (6" N frame) Ruger New Model Blackhawk (the large frame one), A Contender (10"), a Desert Eagle and a Marlin 1894 carbine. Got rid of my K frames years ago, and won't consider anything smaller, period.
They are big, beefy guns, built to run on full house loads, and do it well.
I also have a selection of .44 and .45 caliber pistols that put the .357 in the shade, in terms of power, and "big boom".
