This article was first published online 8-4-2013
38 Super Brass Test


Brad Miller, Ph.D.

Testing 38 Super Brass

I tested 38 Super ammunition and brass in a 9X23 barrel. Technically, it is the wrong ammunition for this barrel. The Sporting Arms and Ammunition Manufacturers' Institute (SAAMI) strictly advises against using ammunition other than what the gun (barrel) is specifically chambered to use, and they specifically identify this combination. I agree with that advice. I’m not endorsing this practice. This was simply an experiment, and I describe the results of that experiment. I’m not the first person to try this combination. Anyone electing to use 38 Super ammunition in a 9X23 barrel does so at their own risk.

Some 9X23 barrels will chamber 38 Super rounds. The 9X23 Winchester and 38 Super cases are the same length (.900”), and the other cartridge dimensions are very similar, just a few thousandths of an inch different, as are their chamber dimensions (Figure 9). The difference is that the 38 Super is straight-walled and semi-rimmed, whereas the 9X23 is tapered and rimless. The 38 Super’s semi-rim is wider (0.406”) than the 9X23 rim (0.394”), but in practice the 38 Super’s semi-rim measures around 0.400”. The 9X23 chamber is narrower at the front end and wider at the rear. In fact, the 9X23‘s front chamber specification is narrower than the 38 Super case mouth specification. But in practice 38 Super ammunition tends to measure smaller than its maximum SAAMI specifications, and in spite of the dimensional differences, 38 Super ammunition fit in my Nowlin 9X23 barrel without issues and headspaced properly on the case mouth.

Drawings and dimensions are based on SAAMI drawings and dimensions. The red text illustrates dimensions that are different relevant to their potential interchangeability.

Shooting 38 Super brass in a 9X23 chamber might allow them to expand a little more than they would in a 38 Super chamber. SAAMI drawings show that the 9X23 chamber is 0.0034” wider measured at a point 0.200” forward of the breech face (Figure 9) than a 38 Super chamber. It is unlikely that the 0.0034” additional expansion of a 38 Super case would dramatically increase the chance of case failure, though that can’t be ruled out. But the biggest danger is excess bulging or case failure in the unsupported region.

Is 38 Super ammunition safe to shoot in the unsupported Nowlin barrel? My Nowlin barrel offers less case support than my Colt 38 Super barrel (Figure 4). Some factory 38 Super ammunition displayed dangerous bulging in the Colt barrel (see Table 2 on the Factory page), though ammunition from the major manufacturers (Federal, Remington, Winchester) was perfectly safe. Also, some 38 Super brass (e.g. Remington, Winchester) have relatively thin walls (see examples on the Brass page), so case rupture is a legitimate concern if used in the Nowlin barrel.

Three factory 38 Super rounds were tested in the Nowlin barrel: Winchester and Remington 130 grain FMJ, and COR-BON 125 grain DPX HP. The Winchester and Remington ammunition showed no sign of excess bulging in the unsupported region. However, COR-BON’s 38 Super round did show excess bulging, indicating that it was not safe in this chamber. I found evidence of excess pressure from this same round in the Colt 38 Super barrel, too (link).

Based on this result I suggest extreme caution if thinking about shooting factory 38 Super ammunition in an unsupported 9X23 chamber. Depending on the dimensions of the 9X23 chamber, it might not offer the same support as a typical unsupported 38 Super chamber, just like my example. In this instance, not all factory 38 Super ammunition would be safe because of the risk of case failure.

38 Super Brass

Handloaders might find 9X23 brass difficult to come by since only Winchester and Starline make cases for this caliber. Thirty-eight Super cases are more widely available. There are also rimless versions of the 38 Super, and they will easily fit in a 9X23 chamber. These include 38 Super Comp (Starline), 38 TJ (TJ = Todd Jarrett, made by Starline, and in the past, Hornady), 38 Super Lapua and Armscor 38 Super rimless. The rimless brass have a narrower rim (0.380 - 0.386”) than the 9X23 (0.394”) and might require tuning the extractor and/or ejector for reliable operation.

The advantage to handloading 38 Super cases is that you have control over how hot they are loaded so you can maintain a margin of safety. What follows is a series of tests designed to determine the safety of various 38 Super brass at 9X23-like pressures in my unsupported 9X23 barrel. The cases were different with respect to case wall thickness and strength, and 9X23-like pressures were too much for several of them.

Case Wall Thickness

How well does case wall thickness correlate with it’s ability to withstand high pressure? The Winchester 9X23 brass, with it’s extra thick wall, tolerates the high pressure very well in an unsupported chamber. But its case wall is substantially thicker than any 38 Super brass. What about the thinner-walled 38 Super cases?

I examined six different brass: Remington 38 Super +P, Starline 38 Super +P nickel plated, Starline 38 Super Comp, Starline 38 TJ, Lapua 38 Super and Hornady 9mm Steyr (1). The 9mm Steyr is another straight-walled case (diameter 0.380”) with the same length and a minimal rim, only 0.001” according to several sources, very much like rimless 38 Super.

I measured case wall thickness of brass that had been sectioned longitudinally like the examples in Figure 5A. The forward edge of the feed ramp imprint on bulged cases measured 0.270” up from the base. I measured case wall thickness at that position (Table 5). The Winchester 9X23 brass was the thickest measuring 0.047” and the Remington 38 Super +P was the thinnest at 0.024”. The Starline 9X23 Comp measured 0.034”.

For “bulge” testing I loaded virgin cases with Silhouette to duplicate the 9X23 factory velocity and a Hornady 124 grain FMJ FP bullet at 1.245” COL. The results are summarized in Table 5.

The Starline 9X23 Comp, Lapua 38 Super, Starline 38 TJ and Remington 38 Super +P cases had dangerous bulging (Figure 10). One Remington case blew-out in the unsupported region. The Starline 38 Super +P nickel plated brass fared better but consistently had a small feed ramp impression.

Examples of the degree of bugling. The Winchester 9X23 case shown here has a “microscopic” imprint of the feed ramp (white arrows). It is difficult to see here but is evident upon magnification. The red arrow marks a large imprint, the yellow arrow marks a small imprint.

The Starline 38 Super Comp and Hornady 9mm Steyr cases fared best. They showed either no feed ramp imprint or only a small imprint. However, they were not quite as durable, on average, as original Winchester 9X23 cases since their feed ramp imprint was more frequent and larger than seen with the Winchester cases.

I conducted further tests with the 38 Super Comp and 9mm Steyr cases. Both of these brass fared well with high velocity/pressure loads and could duplicate factory loads in the 1450 fps range with 3N38 and Accurate #7 without excess bulging, or at most the occasional small feed ramp imprint. Thus, of the brass tested, these were the most durable next to the original Winchester 9X23. Given that some did have a small feed ramp imprint, it would be wise to load them down a little for safety.

I also compared the maximum charge weight of Silhouette that Remington 38 Super +P brass would handle without bulging, just as I did with the Starline 9X23 Comp brass (Table 4). Interestingly, their maximum charge weight was the same, at 6.6 grains with a 124 grain bullet. Thus the Starline 9X23 brass was no stronger than the Remington brass even though it was .010” thicker (Table 5).

These tests revealed that case wall thickness did not correlate well with its pressure performance. The Starline 38 Super Comp and Hornady 9mm Steyr that showed little excess bulging were slightly thinner (0.030”) than the Starline 9X23 Comp (0.034”) that showed dangerous bulging.

This is important to bear in mind because brass thickness is only one variable in its ability to withstand pressure. Brass can differ in it’s strength, according to Starline’s website, by changing its grain structure and heat treatment. Therefore, estimating how much pressure a case can withstand based solely on wall thickness might under- or over-estimate it’s capability.

I only measured one case for each example, and there could be variation from one to another. Also, case wall thickness might not be symmetrical depending on the precision and alignment of the dies used to form the brass, so some brass might be noticeably thinner on one side than the other. I measured both sides of my samples, and they were within 0.001” of each other, but this might vary. Brass strength (and case wall thickness) might vary from one lot to another. My results might be different if I had tested different lot numbers of the same headstamp.

There was considerable variation in Starline’s product line, with the 9X23 Comp and 38 TJ showing a large excess bulge, the 38 Super +P nickel plated a small but consistent excess bulge, and the 38 Super Comp brass showing no, or only a small, excess bulge with the same powder charge. This suggests that either the expectations differ for their product lines, or simply that durability varies with different production runs.

9X23 test pistol. Ready for duty!

My tests certainly push these brass to the extreme, because the 9X23-like pressures are the highest of any semi-automatic pistol cartridge. Many competition pistols used in practical shooting sports that require high velocity performance are wisely built with fully supported chambers to ensure safe operation at the pressure required to achieve the designated power levels. Many of these brass are used almost exclusively by the competition crowd, and probably are seldom used in barrels without good case support. Also, the 38 Super and 9mm Steyr operating pressures are well below the 9X23’s range and are not usually exposed to this type of pressure in the first place. Thus it should come as no surprise that these brass don’t handle 9X23-like pressure as well as the original Winchester case because they were never designed to.

These results emphasize the considerable variation in how brass will respond to high pressure. Thus, using brass other than the original Winchester 9X23 cases for high pressure loads in an unsupported chamber requires testing in your barrel. Always start with reduced loads and work your way up. As soon as you see evidence of excess bulging, you’ve gone too far.

Consider even a small feed ramp imprint an indication that the powder charge is too high. I advise this because of variation I saw in the size of the bulge. Not every brass of the same headstamp responded the same to a given powder charge, though most were consistent. For example, the Lapua 38 Super brass showed a wide range of response to the same powder charge. Some showed only a small bulge, while others had a huge bulge and were probably near failure.

If you have the option, use a slower gunpowder for your high-velocity loads to give yourself an extra margin of safety. Silhouette produces high pressure at these velocities, so I lean toward using 3N38 for high velocity loads in an unsupported chamber because it produces less bulging. For example, it replicated 9X23 factory velocities in my samples of Starline 38 Super Comp, Starline 38 Super +P nickel plated and Hornady 9mm Steyr brass without excess bulging in my barrel.

Always error on the side of safety during load development, and give yourself a wide margin for error just to be safe. Case rupture is very, very dangerous. When in doubt, use only Winchester 9X23 cases for high pressure loads in an unsupported chamber, and reserve the other brands of brass only for reduced pressure loads. Remember, brass should be discarded if the imprint is present as it is likely weakened there and might fail if reloaded and exposed to high pressure again.

One last issue is that excessively expanded 38 Super brass might not resize well, or would end up with bulge/resize artifact that would weaken the case (see Figure 4B here). This was not a problem with my 38 Super cases that did not show excess bulging. They resized down to 0.383-0.384” (Dillon 38 Super size die), the same as they resize when fired in my 38 Super chambers. But not everyone that has fired 38 Super brass in a 9X23 chamber has had that same positive experience and report sizing artifacts. This is something you’ll need to watch for. It likely depends on chamber dimensions, pressures, brass selection and brass life.


Factory 38 Super ammunition might not be safe in a 9X23 barrel if it does not offer full case support, because some factory 38 Super ammunition was not safe in the test barrel.

Thirty-eight Super brass, including the rimless versions, vary in their ability to withstand high 9X23-like pressure in an unsupported chamber and most require reduced charges. Careful testing can determine their upper limit; excess bulging with the appearance of a feed ramp imprint.

By the way, I don’t recommend that you shoot 9X23 ammunition in a 38 Super chamber. 9X23 rounds will fit in some 38 Super chambers, but not all because the 38 Super chamber is a little narrow at the rear where the 9X23 is wider. Even minor expansion might make it stick in the 38 Super chamber. Also, the throat dimensions for a 38 Super chamber are rumored to be different and result in more pressure than a 9X23 chamber. This will only increase the chance that the 9X23 case will expand and stick. I’ve tried this and had a 9X23 case get stuck. It was very difficult to remove, and required a squib rod and a BIG hammer.


The author is not responsible for mishaps of any kind, which might occur from the use of factory or handloaded ammunition. It is the user’s responsibility to follow safe shooting guidelines and to develop safe handloads.

Footnote 1. The Hornady 9mm Steyr cases have a case thickness similar to the Starline brass. I don’t know what the case wall thickness/durability is for “typical” 9mm Steyr brass since I’m not very familiar with this cartridge and only had this one brand example, so my results apply ONLY to the Hornady brass.


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.

Barnes, F.C. 2006.  Cartridges Of The World, 11th Edition, Edited by S. Skinner, Gun Digest Books, Iola, WI.

Brown, E. (1998) 9x23 in “Condition White”, American Handgunner, September/October, pp. 55-56.


8-10-2013. Added Part 2.

11-21-2013. Added photograph of the test pistol.

All images are the intellectual property of Brad Miller, Ph.D. © August 2013.

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