October 18, 2018
By Brad Miller, PhD
The .38 Super is one of my favorite pistol cartridges. It offers versatility, more magazine capacity, reliable feeding, and great accuracy. It is one of the best cartridges for handloaders who can take advantage of its full potential. The .38 Super’s versatility means it is capable of producing light target loads with low recoil and, when handloaded with the right powders, rounds with the same power as the .357 Magnum.
It’s a medium caliber, so it offers more magazine capacity than cartridges of larger diameter. For example, a Model 1911 magazine holds eight .45 ACP cartridges, nine 10mm Auto cartridges, and 10 .38 Super cartridges.
The .38 Super feeds reliably. Its 1.280-inch length has a big part in this because of the angles at which long rounds feed compared to short rounds in the same gun design. Another positive feature is the straight-wall design. A straight-wall cartridge stacks better in single-column magazines than tapered rounds like the 9mm Luger. Tapered cartridges nosedive more than straight-wall cartridges during feeding in single-column magazines, and nosedives can lead to feeding malfunctions.
The semi-rim of the .38 Super is the cartridge’s one flaw. John Browning designed the .38 Automatic, the .38 Super’s parent cartridge, in 1900. It is the same dimensionally as the .38 Super, with a semi-rim on which the cartridge was supposed to headspace. It worked okay in the older-design guns, but it wasn’t necessary. It’s easy enough to make a semiautomatic cartridge headspace on the case mouth, but Browning didn’t incorporate the rimless design until later. The .32 ACP (circa 1899), 9mm Browning Long (circa 1903), and .25 ACP (circa 1905) had a semi-rim, but the .45 ACP (circa 1905) and .380 ACP (circa 1908) were rimless.
The semi-rim tends to feed well from single-column magazines but can cause headaches when feeding from double-column magazines. The semi-rim promotes nosedive as it rubs along the underlying cartridge while the round is stripped from the magazine. If you’ve ever tried to manually unload a fully loaded magazine of semi-rimmed .38 Supers, you know how much force it takes to strip that top round. The semi-rim rests in the extractor groove of the underlying round, and in order to move the top round forward, it has to push all the underlying rounds deeper into the magazine under all that magazine spring pressure. It gets easier to strip the top round as the magazine is emptied. To overcome the deficiencies of the semi-rim, the rimless .38 Super Comp was created. It makes the .38 Super the perfect round for all magazines, single- or double-stack. One might need to adjust extractor tension when switching from semi-rimmed to rimless brass, but for many guns, the extractor can be adjusted to work reliably with both types.
The .38 Super is a very accurate cartridge, something not so well known to many shooters just a few decades ago. In fact, many Colt Super 38 1911 pistols had a reputation for poor accuracy. The problem was traced to excessive headspace. The chambers were cut too deep because the round was expected to headspace on the semi-rim. The problem was that the semi-rim could slide past the cutout in the barrel’s hood, allowing the round to slip too far forward and essentially headspace off the extractor. Accuracy suffered.
John Rollins and Richard Shockley identified the problem and sleeved the barrel chamber so the cartridge headspaced off the case mouth. They described this in an article in the June 1961 issue of American Rifleman. Once properly headspaced, accuracy improved.
Most people associate high velocity with the .38 Super and rightfully so. With the right powder, it can push light- and mid-weight bullets as fast as the .357 Mag. does from a 4.0-inch barrel, but it can also be downloaded to powderpuff loads. The .38 Super and the .38 Automatic differ only by their pressure limits. The .38 Automatic’s maximum pressure limit is 26,500 psi (23,000 CUP), and the .38 Super’s maximum pressure limit is 36,500 psi (33,000 CUP). This means handloaders can use .38 Automatic data to produce low-recoil target loads. Hornady has load data for the .38 Automatic, and many of Lyman’s starting loads for the .38 Super fit in this category as they are at or below the .38 Automatic’s maximum pressure limit. If you consult the Hornady manual (up to and including the 10th edition), the overall lengths listed in the .38 Automatic data are too short. Use the overall length for the .38 Super data.Bullets & Powders
The .38 Super has traditionally used 0.356-inch jacketed bullets. Why? It’s a .38-caliber cartridge by name, and .38-caliber semiautomatic cartridges, at least those created by John Browning, use 0.356-inch bullets.
There are very few 0.356-inch jacketed bullets available for handloaders—literally just a couple—so this means we’re stuck with something else, usually 0.355-inch 9mm bullets, of which there are scores.
One can also use 0.357-inch bullets in the .38 Super. Yes, those traditional revolver bullets can be fired in your semiautomatic pistol, if they fit properly in your gun’s chamber, and many chambers handle them just fine. In fact, Hornady’s handloading manual includes 0.357-inch bullets in the load data for the .38 Super, specifically 125-grain and 140-grain XTP bullets, along with 0.355-inch bullets, and their one remaining 0.356-inch bullet, the 125-grain HAP. Hornady also has load data for the 110-grain .357 XTP for the lower-pressure .38 Automatic.
The thing to watch for with revolver bullets is exposed lead at the nose. That exposed lead might cause feeding problems because it doesn’t bounce off the feedramp like hard copper jackets. Many jacketed revolver bullets have a jacket that extends to the front of the bullet (like semiauto bullets), with no exposed lead at the nose. They will be the best choice for loading the .38 Super.
If you’re wondering if 0.357-inch bullets are too large, the answer is no. Here’s why. The groove diameter of few barrels exactly match their prescribed bullet diameters. Most of the barrels are oversized compared to their usual jacketed bullet diameters. The nine .38 Super barrels I’ve slugged encompass a range of 0.355 to 0.357 inch. I see the same range in my 9mm Luger barrels. I’ve slugged 18 of them, and they range from 0.355 to 0.3575 inch. Only two of those were less than 0.356 inch.
Schuemann Barrels makes 1911 barrels and recommends jacketed bullets 0.001 to 0.002 inch larger than the barrel’s groove diameter and lead bullets 0.002 to 0.003 inch larger for the best accuracy. World-class shooter Doug Koenig, 18-time winner of the Bianchi Cup Action Pistol Championship, shoots a .38 Super and uses 0.357-inch Hornady 110-grain XTP bullets. Are you convinced? The benefit is that you have a wider range of bullets from which to choose: 9mm, .38 Super, and .38/.357-caliber bullets.
My test gun is a hybrid: a Para high-capacity frame, Caspian slide, and Kart Xact Fit 5.0-inch barrel with a 1:16-inch twist. This one has a groove diameter of 0.3548 inch. (SAAMI calls for a groove diameter of 0.355 to 0.359 inch.) It is not a match-quality custom gun, but the barrel was carefully fitted to the slide by me, and there is no detectable movement during lockup.
Alliant, Hodgdon, Hornady, Lyman, Sierra, Speer, and VihtaVuori manuals were scoured for load data. As one might expect, data varied. Maximum loads in one manual might exceed maximum loads in another manual. All loads in this article were safe in the test gun. Readers developing maximum loads in their guns should work up slowly and watch for signs of excess pressure.
The load data using VV 3N38 is from the VihtaVuori manual using .38 Super Lapua brass (which is no longer manufactured) and the CIP method to measure pressure, which differs slightly from the SAAMI method. Also, VihtaVuori used a slightly higher pressure limit with the .38 Super Lapua (2,500 bar=36,250 psi) than it did for the .38 Super (2,300 bar=33,359 psi). The SAAMI and CIP pressures are not exactly the same due to differences in methodology, but they are very similar. If you’re developing loads with VV 3N38, work up slowly from the starting loads and watch for pressure signs in your gun.
The .38 Super does not require a ramped barrel that provides full case support in order to shoot full-power ammunition. Still, strong brass might prevent excess bulging in the unsupported region of the chamber. I’ve found that Starline’s .38 Super +P and .38 Super Comp brass are very strong and less likely to bulge from high pressure in the unsupported region than Remington and Winchester brass. That said, a ramped barrel generally provides the best support and is required when pushing the .38 Super past its normal operating pressures, such as when competitors load ammunition at Major power factor with some powders.Shooting Results
This article summarizes accuracy testing of roughly 6,000 rounds fired during 2017. Bullets were jacketed flatpoints or hollowpoints between 110 and 147 grains. My experience has been that roundnose bullets can be very accurate in my gun, but not as consistently as FP and HP bullets.
The gun was fired at 25 yards mounted in a Ransom Rest. A single 15-shot group with each load was fired for accuracy. It is my opinion that firing the test rounds into a single group gives a better impression of accuracy and dispersion than dividing the ammo into smaller samples and shooting multiple groups. For example, if all 15 rounds stay within 1 inch, it provides more compelling evidence of the gun/ammo accuracy potential than if three, five-shot groups all were 1 inch or smaller, and the question remained if those three groups would overlap or not.
Many of the tested loads were capable of producing 15-shot groups that measured around 1 inch. With 0.357-inch, 110-grain bullets, group size was as small as 1 inch. Hornady and Sierra bullets produced the same accuracy from my gun’s barrel.
Group sizes with 115-grain and 124/125-grain bullets were the most impressive from my gun’s barrel. Groups under 1 inch were not uncommon. There were test sessions, such as one day when shooting 124/125-grain bullets with 6.0 grains of Silhouette, where different bullets acted like they were competing to see which could produce the smallest group. They were all under 1 inch.
A 130-grain bullet is the traditional weight for the .38 Super, and the Winchester FMJ FP bullet I tested produced very good accuracy with 9.0 grains of VihtaVuori N105 powder. That loading produced a 15-shot group that measured 1.23 inches.
The 147-grain bullets also produced group sizes as small as 1 inch. The Hornady 147-grain XTP bullet was the most consistently accurate of the bullets I tried, but several brands produced excellent results.
Other than the gun, the bullet is probably the most important component in accuracy. In the 115-grain category, the Sierra JHP bullet was the most consistently accurate. In the 124/125-grain group, the Hornady HAP and Sierra JHP bullets were notable.
The Sierra bullets were the most consistently accurate in my gun’s barrel. None of the groups with these bullets exceeded 2 inches. They didn’t always produce the smallest group, but they always grouped well. The odd thing is that the Sierra JHP bullets don’t shoot nearly as well in my Kart 9mm barrel.
The 0.357-inch bullets—110, 125, and 140 grains—all shot very well, but they did not categorically outperform the 0.355 and 0.356-inch bullets. Their accuracy was the same in my gun’s barrel.
Several powders stand out for producing excellent accuracy with many different bullets, including Bullseye, Unique, Silhouette, Power Pistol, W572, N340, N105, 3N38, and Longshot. Of these powders, N105 was the most consistently accurate with many bullets and a wide range of charge weights. This is a slow-burning powder that also goes by the name “Super Magnum” as it is considered a magnum pistol powder.
Powders for low-velocity, low-recoil loads that produced excellent accuracy include W572, Bullseye, N320, N340, Target, and Sport Pistol. Powders with a medium burn rate, Silhouette and Power Pistol, also produced small groups at low charge weights.
For high-velocity loads, Accurate No. 7, 3N38, N105, BE-86, Power Pistol, and Silhouette are good choices.
If you’re loading for a pistol with a compensator, a powder that requires a large charge weight will provide more gas for the compensator. These powders include Accurate No. 7, 3N38, N105, Blue Dot, and Lil’Gun. These are slower-burning powders and help keep pressures low when producing the high velocities necessary to make Major power factor required by competition shooters.
What impressed me was the large number of bullet and powder combinations that produced excellent groups. The majority of groups were under 2 inches. Of the 48 loads shown in the chart, 26 were 1.10 inches or less, and 13 were 1.00 inch or less. This speaks very well of the .38 Super’s capability.