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noylj · October 9, 2017, 07:07 AM

cw308:
Sorry, but I disagree about trimming. The cannelure or crimp groove is wider than any case length variation and the very small variation in crimp has NO effect on ANY handgun load I have ever tried: .32 S&WL, .38 Spl, .357 Mag, or .44 Mag. I simply see no reason to trim straightwall cases, ever.
OP:
Please read your manual(s) and learn the terms so we can understand exactly what your question is.
As velocity or pressure goes up, you need more roll crimp for revolver rounds. This is because the recoil will drive the bullets still in the cylinder out of the case. A revolver bullet subjected to high recoil needs to have a cannelure or crimp groove to hold the bullet, so the regular plated bullets are NOT optimum options unless they have a cannelure. If you don't have enough crimp for the recoil forces, the bullet will back out. If you apply too much roll crimp, you cut through the plating and the bullet will be inaccurate and it could go so far as to tumble or separate the plating from the rest of the bullet in air. Beginners should ONLY load jacketed bullets made for that cartridge until they have at least a few hundred rounds under their belts.
For semi-autos, the recoil forces are much different and the only concern is bullet set-back into the case from hitting the feed ramp. Thus, the only "crimp" you need is a slight taper crimp so the flare/bell of the case mouth is removed. What holds the bullet is the case tension and NOT the crimp.
ONLY use loads from a manual. Don't go off on your own until you have some experience. Thus, for .357 Mag, you start with the start load for that bullet weight and powder from the manual for .357 Rem Mag. Even better, check several manuals and start with the lowest start load.
That being said, the start load is not a minimum load and I have often used the same charge weight for .38 Spl and .357 Mag (I don't shoot .38 spl cases in my .357 Mags). The only concern would be taking the charge weight so low (less than 400 fps), that you stick a bullet in the barrel—but, again, for a beginner, don't experiment and use only loads from manuals.

October 9, 2017, 07:07 AM	#7
noylj Senior Member Join Date: October 21, 2007 Location: Between CA and NM Posts: 858	cw308: Sorry, but I disagree about trimming. The cannelure or crimp groove is wider than any case length variation and the very small variation in crimp has NO effect on ANY handgun load I have ever tried: .32 S&WL, .38 Spl, .357 Mag, or .44 Mag. I simply see no reason to trim straightwall cases, ever. OP: Please read your manual(s) and learn the terms so we can understand exactly what your question is. As velocity or pressure goes up, you need more roll crimp for revolver rounds. This is because the recoil will drive the bullets still in the cylinder out of the case. A revolver bullet subjected to high recoil needs to have a cannelure or crimp groove to hold the bullet, so the regular plated bullets are NOT optimum options unless they have a cannelure. If you don't have enough crimp for the recoil forces, the bullet will back out. If you apply too much roll crimp, you cut through the plating and the bullet will be inaccurate and it could go so far as to tumble or separate the plating from the rest of the bullet in air. Beginners should ONLY load jacketed bullets made for that cartridge until they have at least a few hundred rounds under their belts. For semi-autos, the recoil forces are much different and the only concern is bullet set-back into the case from hitting the feed ramp. Thus, the only "crimp" you need is a slight taper crimp so the flare/bell of the case mouth is removed. What holds the bullet is the case tension and NOT the crimp. ONLY use loads from a manual. Don't go off on your own until you have some experience. Thus, for .357 Mag, you start with the start load for that bullet weight and powder from the manual for .357 Rem Mag. Even better, check several manuals and start with the lowest start load. That being said, the start load is not a minimum load and I have often used the same charge weight for .38 Spl and .357 Mag (I don't shoot .38 spl cases in my .357 Mags). The only concern would be taking the charge weight so low (less than 400 fps), that you stick a bullet in the barrel—but, again, for a beginner, don't experiment and use only loads from manuals.