This page was first published online 4-24-2010
(Note: On this page, as throughout this website, the term "38 Super" refers to the 38 Super +P cartridge.)

Some organized shooting sports require that the ammunition achieve a specified power level to be scored in a specified manner. Power factor is determined by the formula: Bullet Weight times Velocity divided by 1000. In the United States Practical Shooting Association (USPSA) rules1, Major power factor in Open division (38 cal. / 9X19 and larger) is 165 (it used to be 175). The 38 Super is eligible for Major power factor only in Open and Revolver division in USPSA rules. In all other divisions (Limited, Limited 10, Single Stack) a larger caliber is required (40 cal. / 10mm or larger) for Major scoring. In these divisions the 38 Super qualifies only for the Minor power factor of 125. All guns in Production division are scored Minor regardless of caliber (38 cal. / 9X19 minimum).

The scoring distinction is that Major power factor gets one additional point for hits outside the "A" zone than Minor power factor. If you shoot all As, then power factor does not matter - you get the same number of points whether you're shooting Major or Minor. But hits outside the A zone lose more points if you're scored Minor. The figure to the right approximates the Metric Target commonly used in USPSA competition and illustrates the scoring zones A-D.

The USPSA is the United States division of the worldwide organization of the International Practical Shooting Confederation (IPSC). IPSC rules2 are similar to the US division. In IPSC the 38 Super is eligible for Major power factor in Open and Revolver divisions. Interestingly, the power factors for these divisions are 160 and 170, respectively.

For the sake of brevity I will generally refer to the USPSA power factor of 165 when giving examples. (In case you haven’t guessed already, I live in the United States.) Including the numbers for all three Major power factors (160, 165, 170) would make reading this text very tedious and potentially confusing, and I would prefer to keep it simple.

International Defensive Pistol Association (IDPA) does not have a division in which 38 Super chambered semi-automatic pistols qualify for Major power factor. IDPA rules3 relegate any semi-automatic pistols chambered in 38 Super to fit into either the Enhanced Service Pistol or Stock Service Pistol Division. All guns in these divisions are scored a Minor power factor of 125. Technically, IDPA calls it a “minimum power floor” of 125,000 that is calculated by multiplying bullet weight by velocity. But a 38 Super chambered revolver could qualify for a 165,000 “minimum power floor” in the Enhanced Service Revolver division.

An easy way to calculate power factor is as follows: Multiply the power factor by 1000. For a power factor of 165, that means 1000 X 165 = 165,000. Now divide this number by your bullet weight to see how fast it must go to reach that power factor. Let’s say you’re using a 130 grain bullet. The formula is: 165,000 / 130 = 1270. (all fractions are rounded up to a whole number.) The formula for a 147 grain bullet is: 165,000 / 147 = 1123 feet per second. Table 1 shows the necessary minimum velocity in feet per second for a variety of bullet weights to qualify for various Minor (120, 125) and Major (160, 165, 170, 175) power factors as defined by some competitive shooting sports.

IPSC limits the minimum bullet weight in Open division to 120 grains. USPSA limits the minimum bullet weight in Open division to 112 grains. There are no restrictions on the bullet weight for Revolver Division in IPSC or USPSA. Heavier bullets are also available in .357 diameter, but their length becomes an issue when loaded in the 38 Super case.

Table 1: Minimum Velocities Required for Minor and Major Power Factors
Power Factor
Bullet Weight *
115
120
121
123
124
125
130
135
140
145
147
150
151
158
160
170
180
120
125
160
165
170
175
1044**
1087
1392
1435
1479
1522
1000
1042
1334
1375
1417
1459
992
1034
1323
1364
1405
1447
976
1017
1301
1342
1383
1423
968
1009
1291
1331
1371
1412
960
1000
1280
1320
1360
1400
924
962
1231
1270
1308
1347
889
926
1186
1223
1260
1297
858
893
1143
1179
1215
1250
828
863
1104
1138
1173
1207
817
851
1089
1123
1157
1191
800
834
1067
1100
1134
1167
795
828
1060
1093
1126
1159
760
792
1013
1045
1076
1108
750
782
1000
1032
1063
1094
706
736
942
971
1000
1030
667
695
889
917
945
973

* Weight in grains. ** All velocities listed in feet per second. All numbers rounded up to the nearest whole number. 120 and 125 are Minor power factors. 160, 165, 170 and 175 are Major power factors.

Very little available factory ammunition for the 38 Super will make Major power factor, but this depends on the gun, or more specifically the barrel. Note Table 2 on the factory ammunition page. Few of the loads tested had a power factor that reached 165 in the test gun, but some were close. Several CORBON loads made Major, but they are expensive and their primary market is self defense.

One company (in the U.S.), Atlanta Arms & Ammo, loads 38 Super and SuperComp ammunition to Major power factor. They are noted on the Factory Ammunition page (see results).

Outrageous Pressure

Because most factory 38 Super ammunition does not make Major power factor, most competitive shooters turn to handloading.  However, this type of performance often means approaching or exceeding maximum SAAMI pressure specifications. Excessive pressure loads run the danger of blown cases in unsupported barrels, which means potential damage to the gun and injury to the shooter and bystanders. A ramped barred that provides full case support reduces the risk of case blowout.

Handloaders discovered that it was possible to make Major power factor with the 38 Super and remain within SAAMI pressure specifications if they used heavy bullets combined with slow burning gunpowders. When the power factor was 175, handloaders often turned to 150 grain and heavier bullets. If you’re familiar with the bullet selection for the 38 Super, usually consisting of .355 and .356 diameter bullets, you’ll know that few heavy bullets with these diameters exist.  Indeed, many shooters turned to .357 diameter bullets typical of 357 Magnum and 38 Special revolver cartridges. Bullets as heavy as 180 grains were used (see Jeff Maass’ 38 Super data at http://www.k8nd.com/ipscload.htm).  With the current USPSA power factor floor at 165, Major can be achieved with 147 grain bullets loaded within SAAMI pressure specifications, and some powders allow the use of bullets as light as 124 grains within safe pressures.  Gunpowder selection is critical. Generally, only the slower gunpowders can achieve this.

Many competitors prefer the use of lighter bullets and/or faster gunpowders. This often means that pressure exceeds the 38 Super’s SAAMI Maximum Average Pressure limit of 36,500 psi (see Technical Specifications). Pressures approaching 40,000 psi and higher are typical. These pressures are dangerous. That said, there are some conditions where these excess pressure loads have been successfully used by competitive shooters. The most important safety component is the use of a barrel with a supported chamber. Loads with pressures that exceed SAAMI specifications should not be used in barrels that do not offer full case support.

Supported chambers

Excess pressure 38 Super ammunition should only be used in a chamber that fully supports the cartridge case. The figure below shows the difference between an unsupported (non-ramped) barrel chamber and a supported (ramped) barrel chamber for 1911 type pistols (for more information see here).

The distinction is how much of the case head above the extractor groove is exposed when the cartridge is chambered. An unsupported chamber leaves some of the case head exposed. A supported chamber leaves little or no case head exposed. Most ramped barrels offer full (or very good) case support, but this varies with gun design and barrel manufacturer. Look yours over closely.

The case walls of most brands of 38 Super brass are not especially thick near the case head. If your pressures are under the SAAMI maximum and you're using a gun with an unsupported barrel (factory specifications, unmodified), you're usually safe and have little risk of case bulge or blowout. But excess pressure can produce bulged cases or a blowout in the unsupported region. Examples of bulged cases are shown here (same Figures as on the Factory Ammunition page).

These figures show examples of case bulge in the unsupported region of 38 Super cases. The cartridges were fired in a factory Colt barrel. The blue arrows mark the "imprint" of the chamber's feed ramp where the case is not surrounded by the chamber. B' shows a close-up of the bulge in photograph B.

Some brass is tougher than others, but they all have limits. If you load your own ammunition and you're looking for the toughest brass, consider Starline or Hornady cases. See the Brass page of this website for more specific information.

Rifle primers

The weak link in high pressure 38 Super ammunition is the primer. Pistol primers are designed to withstand pistol pressures. They are not designed to withstand the excess pressure levels that are sometimes achieved when trying to make Major. Excess pressures can produce cratering, flattening and rupture of the primers. Examples can be found on the Factory Ammunition page (here). The most common fix for this is to use rifle primers. They are designed to handle higher pressures (over 50,000 psi). Because of this they are less sensitive to firing pin strikes than pistol primers. It then becomes important to make sure that the fire control components in the pistol will reliably ignite the tougher rifle primers.

Some rifle primers are more sensitive than others. The “internet consensus” is that Federal small rifle primers are the most sensitive, Winchester small rifle primers are slightly less sensitive than the Federal, and the CCI brand are the least sensitive. I’ve not seen a consensus about the sensitivity of Remington small rifle primers. Some folks rate them similar to the CCI primers, while others claim they are not that hard. I currently use Federal small rifle primers with my over-pressure 38 Super loads, and have not had a misfire yet.  In the past I used CCI small rifle primers. Most of my 1911 pistols are equipped with a 19 pound hammer spring and some have titanium firing pins. On rare occasions I had misfires using CCI rifle primers and titanium firing pins.  When I put a 17 pound hammer spring in one of my 1911s with a titanium firing pin, misfires occurred with greater frequency with the CCI small rifle primers. I switched to Federal Small rifle primers and the misfires were cured. I’ve also used Winchester small rifle primers on occasion, and have not had any misfires with them, but I don’t remember which hammer springs or other components I had in the gun(s) at the time, so I can’t comment with confidence about their relative sensitivity. Remember, your results could be different. I've not used any Remington rifle primers.

Small rifle primers are the same height as small pistol primers, so they seat to the same depth in 38 Super brass.

Load Development

Loading any cartridge to maximum or excess pressures always has risks. Fortunately people have been hot-rodding the 38 Super for years, and there are resources with load data. One of the best can be found at Jeff Maass' website. Another great resource is the Brian Enos Forums. You should be able to find a load at these resources that will fit your needs. Obviously, you'll need a chronograph for testing velocity in your gun.

Talk with other shooters and find out what load they're using. But keep in mind that what might be safe in someone else's gun, might not be safe in yours. See the general guidelines below for load development.

(By the way, I will not be held responsible for any damage that occurs to your gun or any injury to you should you decide to try someone else's load data or to try to develop your own loads. Load development can be very risky, and you must understand that you're headed into dangerous territory when you start working with overpressure loads. Bad things can happen. Including death. You do so at your own risk!)

1. Use only medium to slow burning pistol gunpowders for the 38 Super. Fast burning gunpowders will reach frightening pressures before they make Major. Frankly, you can't always point to a Burn Rate chart and say "Don't use anything above / below this point." Different gunpowders have different characteristics that are not apparent in a Burn Rate chart. Some gunpowders are forgiving of compression, others aren't. Check with the gunpowder manufacturer to see if they have any recommendations. They might not, for fear of liability. You can't blame them. Working with overpressure loads is dangerous!

2. Work up slowly! Start with loads under maximum as listed in a reliable reloading manual and slowly work up.

3. Watch for pressure signs in the primers (cratering, flattening, worse! See the Factory Ammunition page for examples) and cases (bulging, see above). While watching for pressure signs in the primer is inherently flawed (Speer Reloading Manual #14), it's one of the few methods we have. If you see excess pressure signs in rifle primers, you've gone way too far! Try another gunpowder or bullet.

4. Published load data applies only to the specific bullet used for that data. Pressure can vary despite using different bullets of the same weight loaded to the same overall length.

5. Actual pressure will vary with the barrel. If you've developed a load for one pistol without excess pressure signs, it might be too hot for a different gun. For example, I have three different barrels that have three different pressure limits with my excess pressure ammunition.

6. Overall length matters!!!! The deeper the bullet is seated, the greater the pressure. This is especially true for overpressure loads. Watch the cartridge overall length very closely! See the Overall Length page for practical information on determining overall length.

7. Never, ever mix gunpowders. That is called suicide!

8. Be safe and smart. Always error on the side of caution, and you'll be able to enjoy this sport for a lifetime.

1 USPSA Handgun Competition Rules January 2008

2 From their website at: http://www.ipsc.org/ at the Divisions link, January 1, 2008

3 IDPA Rule Book 2005

References:

ANSI/SAAMI booklet Z299.3-1993. American National Standard. Voluntary Industry Performance Standards for Pressure and Velocity of Centerfire Pistol and Revolver Ammunition for the Use of Commercial Manufacturers. 1993. Sporting Arms & Ammunition Manufacturers' Institute, Inc., Wilton, Conn. USA.

Speer Reloading Manual #14 (2007) Lewiston, ID.

Questions, comments, suggestions, hate mail? Feel free to email me. However, the probability of getting a response is low simply because I have a day job and a life and don't have the time to respond to all emails. It's nothing personal, really. Nevertheless, I do appreciate your thoughts. If you see an obvious error then please put the word ERROR in the title of your email. Thanks, and happy shooting.
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