First, concerning wadcutters...
Then I started thinking about increasing magazine capacity...While playing around with COAL with full wadcutters seated out (dummy rounds, no primer or powder), it seems I might have stumbled on a 'sweet spot', because I have dummies in both .38 and .357, BBWC (SNS Casting) and a H&G button nose (Bayou) that feed slicker than snot.
The SNS WC is .574 long, the Bayou is about .576, however, the distance to the shoulder on the Bayou is .068 in back of the nose. That means for a given OAL, the shoulder of the H&G design is going to be about .065-.068 closer to the case mouth.
SNS Casting poly coated boolit (gold).
.358
148 grain BBWC
8 grains Unique (old)
Taper crimp, just below crimp groove. Groove fully exposed.
OAL 1.406
Bayou Bullets poly coated boolit (green).
.358
138 grain (per website) H&G style Button Nose BBWC
15 grains Hercules 2400
Roll crimped in 2nd groove from nose (first lube groove)
OAL 1.475
And finally, load development...My 16" M92 holds 9 .38spl's FMJ flat nose (@ 1.43" OAL) in the tube.
I'm looking at .38 S&W brass, sized through a .357/.38 die, loaded with 125gr RNFP coated boolits, with 4+ grains of Unique (up to 4.5?) at about 945fps (pistol barrel). Add 200 fps for the rifle tube, and it's getting close to 1200fps and kinetic energy in the zone of at least a 9mm.
What's the payoff? The math says that I should be able to get 13-14 of them in the magazine. For an urban self defense gun, I think that is significant...
The biggest unknown right now is how COAL length works out feeding...
So, that's what the fertile imagination has produced so far. I'm not a complete noob, but am far from an expert. Any thoughts/help will be appreciated.Is this a correct way to develop loads? Obviously, I do not want to blow myself up, and also obviously I'd like more performance in the cartridge than normal .38 S&W (NOT .38spl) loads.
Existing load data is always safe for old top breaks, so the range I'm looking for is extremely rare.
I have looked at case dimensions, and the 9mm is very close to the 38S&W, though the 38 is slightly longer, the 9mm is very slightly fatter. I think for my purposes the volume differential is nominal.
So, since the S&W will be sized to .38spl dies, am I correct in thinking that I could look at 9mm cast boolit data, reduce 10% and work up? I'm looking to use coated 125gr RNFP.