Ballistician's Notebook: The 38 Special
January 04, 2011
Allan recommends that new .38 Special handloaders start with lead bullets (right) instead of light, jacketed bullets.
Through both a hobby and a profession, I've been graced with opportunities to look at cartridges from different perspectives. That has led to the concept of a Ballistician's Notebook, where these perspectives could be blended and preserved. I started my handloading career with the .38 Smith & Wesson Special, and I thought the cartridge would be a good place to start with a series sharing some of my more interesting findings and perspectives.
I won't rehash the cartridge's history other than to remind you that the .38 Spl. falls among a group of cartridges that started life loaded with blackpowder and successfully made the transition to smokeless propellants. As a result, the cartridge case is larger than needed for modern propellants. This can work against the incautious handloader.
Pressures & Case Capacity
The .38 Spl. has two pressure levels; one, at 17,000 psi, is for older firearms or those built on very light frames, and the other, 20,000 psi, is for modern firearms with the latest metallurgical enhancements. The upper level gets the designator .38 Spl. +P. For comparison, the maximum average pressure (MAP) for the .22 Long Rifle is 24,000 psi.
The relatively large case and the modest pressure limits have created an unusual situation: People suffering .38 Spl. problems from too little pressure are a significant percentage of those encountering problems. This is a cartridge whose lower charge limits must reflect a certain minimum pressure. Bullet type has an inordinate amount of influence. This is especially important with jacketed bullets that produce more friction in the bore than lead-alloy bullets. It doesn't take much powder to run light loads, and these small charges look lost in a .38 Spl. case. With so much case space, the powder charge has to maintain enough pressure to keep the bullet moving.
Reloaders should use caution in loading the .38 Spl. to low recoil levels. Lubricated lead bullets have far less resistance in the bore than jacketed ones. I recommend that the novice .38 Spl. reloader always begin with lead projectiles of 145 grains and up. In recent Speer manuals, we did not show "start" loads for some jacketed bullets at standard . 38 Spl. pressures. Variations in critical chamber and barrel dimensions in some revolvers caused some velocities to fall to the point where lodging a bullet in the bore--a condition abbreviated BIB--was possible.
For revolvers, barrel/cylinder gap will always be a negative factor. The faster-burning propellants are preferred for loading light, jacketed bullets at less than maximum pressures. The bullet has a little more velocity by the time it crosses the gap, and any gas loss is somewhat mitigated. The industry guideline for the maximum gap in a revolver is 0.012 inch; I feel more comfortable with .38 Spl. revolvers that are 0.008 inch or less.
Cowboy action shooting revealed that in attempting to reduce recoil to negligible levels, some reloaders took the "light bullet/light charge" concept too far and got BIBs. It turned out the pressures were often in the range of 5,000 to 6,000 psi--simply not enough for modern propellants. When we developed loads for any revolver cartridge that could be used in cowboy competition, we did not let the start loads fall below 10,000 psi.
A too-small bullet for your revolver's chamber throats can work against you. The cast-bullet hand-loader has an advantage over his counterpart shooting jacketed bullets. If he casts the bullets himself or buys them "in the raw"--that is, not sized and lubed--he can size bullets to larger diameters than available in regular production orders. The advantage is that pressure stays up longer. With lead bullets up to 0.360 inch, it's nearly impossible to size the bullets large enough to cause severe problems in a .38 Spl.
If you know you want to load light and plan to stick with published starting loads, choose from the faster-burning propellants. That will keep the start pressures higher to help you avoid problems.
The accompanying chart shows how pressures required to produce 1,000 fps in a pressure barrel (a fairly light load for 110-grain bullets) will change with burn rate.
If you want to develop a light load, don't load up hundreds of cartridges before testing in the revolver you plan to use. Load a few and, if you have access to a chronograph, look for velocity variations.
Establish a base line by elevating the muzzle before each shot to put the powder at the primer. Then test again, depressing the muzzle before each shot. This puts the powder at the base of the bullet, an orientation most likely to show ignition and burning issues. The velocity will go down somewhat but should not drop more than about 50 to 75 fps in a good load.
Do this testing slowly so you can listen for a BIB. Any "off" sound should have you checking the bore. Once satisfied that the load is consistent in the firearm(s) for which it is intended, load the larger quantity.
The disadvantage to a century-old cartridge is the variation in cartridge case manufacture over that time. The big change since the mid-1980s has been a gradual thickening of the case wall near the case head. This changed case capacity, and using mixed cases will add more velocity variation. The old advice to segregate cases by brand needs to be extended to separating by headstamp and other factors like factory cannelures rolled into the case body.
Those rolled cannelures can control your choice of what bullet goes in what case. I have a lot of old Remington cases that have a very heavy cannelure near the case mouth. This cannelure seldom is completely ironed flat after firing and resizing. If I try to seat a jacketed bullet in the case, the hard wall of the bullet pushes the cannelure out and can create chambering problems. On the other hand, that pesky cannelure nicely snaps into the center of the big lube groove on the Lyman/Ideal No. 358429 cast bullet--the classic Keith design--so I save those cases for loading that bullet.
A person could experiment for years with the .38 Special and not find all its interesting abilities. It remains today an accurate and useful cartridge over 100 years after its introduction.