Super Powders for the .38 Super
August 20, 2015
If you shoot a .38 Super, you might lament its loss of performance over the years. Back in the old days, the standard load for the .38 Super was a 130 grain bullet zipping along at 1300 fps. That load was introduced in 1933 by Remington, for Colt's Super .38 pistol, which was introduced in 1929. Today, that same bullet has an advertised velocity of 1200-1215 fps.
If you want performance from factory .38 Super ammunition nowadays, you have to turn to one of the boutique ammo makers such as Atlanta Arms, Buffalo Bore, CORBON, Georgia Arms, Underwood or Wilson Combat. They drive a 124/125 grain bullet up to 1350 fps.
The other option is to load your own ammunition. In fact, if you choose the right powder, you can turn that .38 Super into a super-screamer. Some of the published velocities for this round are real head-turners, with claims of pushing 124/125 grain bullets from 1400 to 1500 feet per second (fps). Now, don't confuse these with souped-up, hot rodded .38 Super ammo that some folks use in competition and are at excess pressure and require a ramped barrel. These published loads are all within SAAMI or CIP industry standard pressures, so they should be safe for all .38 Super barrels.
Four gunpowders were tested to see if their published velocities were realistic, and if they were, in fact, safe in a standard, unramped barrel. The test gun was a stainless steel Colt Government Model (5" barrel). The Colt barrel does not offer full case support since there is some portion of the case head exposed above the extractor groove. This is common with unramped barrels, and even some ramped barrels.
I scoured loading manuals that provided top speeds for the Super and found what I desired in the Western Powders, Vihtavuori and Sierra manuals. Velocities in some other manuals (Speer, Hornady, Hodgdon) are high with some powders, but were either less than the speeds in the manuals mentioned or I could not get the powder (for example, Hodgdon Lil'Gun).
The Western Powders manual lists some impressive performance in the .38 Super with Accurate No. 7, so its data was tested with all the bullets they listed to see how it measured up. Their maximum loads are at high pressures, but still under the SAAMI specification maximum for this cartridge, 36,500 psi. One number caught my eye because the listed velocity was an even 1300 fps. But this was not for a 130 grain bullet. No, this was for a 147 grain lead bullet. That's the type of performance we're looking for!
The Vihtavuori manual lists one outstanding powder for the .38 Super: N105 Super Magnum. For example, it claims to push a 124 grain bullet to 1501 fps in a 5.5" barrel. Naturally, it was included in the test.
The Sierra manual lists several powders that produce high velocities. The top performing powders that will reach 1450 fps with 115 grain bullets include Power Pistol, 540, Winchester Super Field (WSF), and Accurate No. 7. For the 125-130 grain bullets, Universal Clays, Power Pistol, WSF, Accurate No. 7, N105 and HS-7 make the top velocity of 1350 fps. HS-7 is no longer available, and 540 has been rebranded as HS-6. I tested Power Pistol and WSF.
There is some discrepancy in the data between different load manuals. The discrepancy can drive you nuts, but it's fair to say that they report the results they found with their test equipment and components. It's important to keep in mind that every barrel is different, and different lot numbers of components, especially the gunpowder, will yield different results. That's why you have to work your loads up carefully in your gun to determine what it will safely handle.
No two barrels are alike, and I have two .38 Super barrels that react differently to the same load. The same load will show pressure signs in one barrel but not in the other. Different chamber and bore dimensions are the likely cause of their distinct reactions. But loads that appear safe in one barrel might not be safe in another. This applies to the results of this test. Just because these loads are safe in my gun does not mean they are safe in yours. Work the loads up slowly and watch for signs of excess pressure.
I looked for pressure signs in the primers and brass. Reading primers for excess pressure is always tricky because they are not very good bellwethers. But it's one of the few tools we have, so we use it.
The other method was to look for excessive case bulging at the unsupported region of the chamber. If the brass expands too much, a stamp or imprint of the feed ramp can be seen on the brass. If you see this mark, you've passed the safety limit of the brass and need to reduce the powder charge. Excessive pressure can cause the brass to rupture here with a blast of dangerous case fragments and hot gas, which can damage the gun and injure the shooter.
I used the same brass, primers and overall length to replicate the published data. I also tried to use the same bullet brand when possible. Accurate No. 7 was loaded in Winchester brass, N105 in Remington nickel-plated brass, and Power Pistol and WSF in Starline +P nickel-plated brass. The published data for Accurate No. 7, Power Pistol and Winchester Super Field are from a 5" barrel, and the published data from Vihtavuori is from a 5.5" barrel.
Accurate No. 7
The published charge weights for all bullet weights produced velocities that exceeded even the impressive published velocities by 50 fps or more (see Table) when loaded with Accurate No. 7. The 115 grain bullets were at or exceeded 1550 fps, the 124/125 grain bullets were at or exceeded 1450 fps, and the 147 grain bullets exceeded 1300 fps.
Several of the loads exhibited some evidence of excess case bulging of the Winchester brass in the unsupported region of the Colt chamber, so I reduced the charges until the excess bulging was no longer visible. Loads for the 147 grain bullets had to be reduced to under 1200 fps to prevent the bulge from appearing.
This magnum performance powder does not disappoint. The velocity with the 124 grain bullet (1457 fps) was a little short of the published speed of 1501 fps, but the published speed was from a slightly longer 5.5" barrel. The velocities of the 130 and 147 grain bullets were right on at 1392 and 1236 fps, respectively (see Table). There were a couple of bulged Remington cases with the 124 grain load, but dropping the load a mere 0.2 grains was enough to fix that and still produce high velocity.
Power Pistol and Winchester Super Field
Velocities with 115 grain bullets with both of these powders exceeded their expected 1450 fps by at least 20 fps (see Table). They performed even better with the 125 grain bullets, exceeding the expected 1350 by at least 50 fps. None of the Starline brass showed excessive bulging in the Colt barrel.
Not all brass is the same, and some brands will show excess bulging while others won't with the same load. My experience suggested that Starline +P brass is more durable than Winchester and Remington, so I loaded Starline and Remington brass with some of the same maximum Accurate No. 7 loads and bullets that produced excess bulging in the Winchester brass to see how they compared.
With the 115 grain lead bullet and 11.0 grains of Accurate No. 7, 9 out of 10 Winchester brass had excess bulging in the Colt barrel. With this same load, 6 of 10 Remington brass showed excess bulging, while none of the 10 Starline brass did. With the 147 grain Speer bullet and 9.0 grains of Accurate No. 7, 7 of 10 Winchester and 4 of 10 Remington brass had excess bulging, but none of the 10 Starline brass did. This suggests that the Starline +P brass is tougher in the unsupported region than Winchester or Remington. It allowed this barrel to take full advantage of Accurate No. 7's potential to produce high velocities. The loads in the Starline +P brass produced 1587 fps with the 115 grain bullet and 1311 fps with the 147 grain bullet. Other shooters might also find this brass beneficial in their unramped barrels.
.357 Magnum Performance
The .38 Super can produce real .357 Magnum performance from a 5" barrel, just like the 9X23 Winchester, with the right gunpowder. The benchmark load for the .357 Magnum propels a 125 grain bullet at 1450 fps from a 4" barrel. Accurate No. 7, N105 and Power Pistol can all do that with a 5" barrel.
Some people would argue that the .38 Super requires 1" more barrel than the revolver for that speed, but a semi-auto's barrel measurement includes the chamber while the revolver's barrel does not. If you subtract the .38 Super's case length of 0.900" for the cartridge chamber from a 5" barrel, you now have a 4.1" barrel. Also, a 5" barreled .38 Super is shorter than a 4" barreled .357 Magnum revolver. A 4" Smith and Wesson 686 is 9.56" long, and the 5" Colt Government Model is a full inch shorter at 8.5" long. Thus the .38 Super offers the same performance in a smaller package.
In addition, the semi-auto carries more ammunition. Three-fifty-seven Magnum revolvers are limited to five-to-eight rounds, whereas the semi-auto pistols can hold 10 rounds or more, giving the semi-autos a distinct advantage in firepower. My high-capacity Para Ordnance .38 Super pistol holds 18+1 rounds with a standard length magazine. That's three times what a six-shot revolver holds. That's serious firepower.
Many powders will easily make Major power factor with all bullet weights within normal pressure limits. IPSC/USPSA shooters will welcome this fact. The .38 Super can produce impressive velocities with the right gunpowder. Chamber support is important and those barrels that don't offer full support require caution in developing handloads to avoid the risk of case rupture. Fully supported chambers reduce this risk and offer handloaders the safest way to maximize performance, but these results show that even the unsupported factory Colt barrel is capable of handling some very high-powered loads.
The Starline .38 Super +P brass handled high pressure loads with less chance of excess bulging than Remington and Winchester brass. However, even the Starline brass has limits so don't expect it to protect you from reckless loading practices. Always start low and work up slowly watching for pressure signs.
The author is not responsible for mishaps of any kind which might occur from the use of this data in developing your handloads. It is the user's responsibility to follow safe handloading guidelines to develop safe ammunition. You use this data at your own risk. No responsibility for the use or safety in use of this data is assumed or implied.