View Single Post
Old May 22, 2018, 01:01 PM   #38
labnoti
Senior Member
 
Join Date: April 2, 2018
Posts: 110
Shortening the .38 Special does have some advantages. Because the .38 Special was originally a black-powder cartridge, it has excess case volume which makes it:

powder position sensitive - if the powder is knocked forward in the cartridge it will ignite and have a different pressure curve than if the powder were knocked back toward the primer. This results in wider ES and higher SD and inconsistencies in velocity and in some cases, point of impact and hollow-point expansion.

require a long extractor rod - most snub nose revolvers have short ejector rods that only push the cases part way out, depending on inertia, or gravity to complete the ejection and if conditions fail, they must be pulled out with fingers.

excess cylinder length - revolvers could be made more compact overall or they could be given longer barrel lengths without increasing the overall length

9x19mm and .380 ACP offer similar ballistics to the .38 Special but in cartridges of dimension intended for use with smokeless propellants. The 9x19 typically has a higher power factor because of the higher pressure rating specification. It should be apparent that 19mm is sufficient case capacity for the .38 Special's power factor goals using smokeless propellants.

The .45 ACP was developed specifically to have similar ballistics to the .45 Long Colt, but using no more case capacity than necessary with smokeless propellants.

.45 ACP, 9x19mm, and .380 ACP do not typically work well in revolvers because they are rimless and they are typically taper-crimped instead of roll crimped. Using factory production cartridges in a revolver will require the use of moon-clips and the bullets are more likely to jump the crimp. It is probably easier to add a roll-crimp to the 9x19mm cartridge than it would be to add a rim to it. The bullets should also feature a cannelure or crimp groove, which are not typical of .356" diameter bullets.

Roll-crimping short cases would require a die that is for a suitably short specification. My LEE factory crimp die for .38 Special bottoms out at 1.050". It could be modified by removing material from the bottom and reforming the mouth on a lathe. A .38 Short Colt die would work perfectly.

While loading shortened .38 Specials, which are essentially .38 Short Colt, to .38 Special pressures could eliminate powder-position sensitivity and make ejection with short ejector rods more positive, there isn't published data for loading to .38 Special pressures with the shorter OAL. Seating wadcutters deeply usually requires light powder charges to avoid overpressure conditions. When the base of any type of bullet is seated that deeply, the pressure with the same charge as standard OAL cartridges is going to be greater. Of course, wadcutters are proof that it can be done in the .38 Special.

The last issue, the excessive length of the cylinder, could only be addressed by the manufacture of revolvers for a shorter cartridge, either 9mm or .38 Short Colt. To do this properly would involve either making a 9mm rimmed cartridge or establishing a cartridge nearly identical to the .38 Short Colt but with a pressure specification similar to 9mm Luger.

It seems the .32 caliber revolvers could also benefit from a high pressure rated cartridge without the excessive length of something like the .327 Federal Magnum.

I was never fond of the notion that a cartridge must have an excess of length to prevent it from being loaded in a firearm that is unsuitable for the pressures it will generate. As a reloader, I have always had the freedom to exceed maximum pressures and blow guns up at risk to my own life, and cartridge length has never protected me from that.

This reminds me of the optimist who says the glass is half full, the pessimist who says it's half-empty, and the engineer who says the glass is twice as big as necessary.

Last edited by labnoti; May 22, 2018 at 01:06 PM.
labnoti is offline  
 
Page generated in 0.03364 seconds with 8 queries