The .45 Auto Rim has never been what anyone would call a big seller. For years it was available from Remington in a 230-gr. LRN @ approximately 800 ft/sec. Ammunition was expensive and lackluster in performance, but very nice things could be done if a handloader.

Were it not for revolvers being made for use with .45 ACP via moon clips, I think the auto rim would be a dead cartridge. For years the only manufacturer of either loaded ammunition or cases was Remington. Starline Brass now makes new cases in this caliber.

I believe the auto rim may be saved from extinction for a number of reasons. First, many states have passed concealed carry laws so that more folks are interested in a compact carry gun and more than a few prefer revolvers. Of those, there are people who simply do not trust the "small bores" and believe that a defensive cartridge's caliber designation should start with a "4". Thus, there are some .44 Special, .45 Colt, and .45 ACP revolvers. Other than some convertible .45 ACP/45 Colt single-action revolvers most are traditional double/single action and have swing-out cylinders. In order to hold the cartridge for positive firing and consistent positioning as well as ejection, moon clips are required. These are available in two forms: full moon, which holds a full six in the case of .45 ACP and half moon, which holds three.

The use of moon clips is almost universally acknowledged as a pain in the rear end. They can be difficult to load and are always a little slice of hell to unload. Tools to make removal of empty hulls do exist in various forms and I use a rather inexpensive one myself.

Corbon is a name long associated with throttle-to-the-firewall +P loads that almost always led the pack with regard to velocity, but they also make heavy bullet hunting loads as well and offer more than one approach to enhanced performance defense ammo. Their latest is the DPX line of anti-personnel cartridges.

DPX stands for Deep Penetrating X-bullet. The X-bullet from Barnes is made completely of a copper alloy and contains no lead. There is no jacket. There is a hollow point to be sure, but the bullet is of the same material through and through. In the manufacturing process, the bullet is designed to expand via six equidistant petals compared to four common to the Barnes line of rifle-caliber X-bullets.

One of Corbon's latest additions to their DPX family of defense ammunition is the .45 auto rim. It is a standard pressure load. The nominal muzzle velocity is listed as 1050 ft/sec, but their website gives no barrel length used for this figure. For all intents and purposes, it is their .45 ACP Compact Gun Load being offered for .45 ACP revolver shooters in a cartridge that negates the need for moon clips.

I recently obtained some of this new ammunition. The only .45 ACP revolver I own is a Smith & Wesson Model 625 with a 5" barrel. This is hardly an ideal concealed carry revolver but it's what I had. I expected velocities to be a bit higher than the published 1050 ft/sec and they were.

Using this one revolver, I checked the ammunition for a number of things including accuracy, felt-recoil, and consistency over the chronograph. I also performed my own informal expansion testing using both water and super-saturated newsprint I soaked for 24 hours and drained 30 minutes before shooting.

Shooting: All shooting in today's test was done in slow-fire, single-action, and from a seated position with my wrists braced. I wanted to see if the load was accurate. Though such luxuries are not present in the situations for which this defensive ammo is intended, I personally have no use for ammo that cannot group to my satisfaction. For me, inaccurate or inconsistent ammunition is not acceptable. I was not disappointed.

I fired at distances of 15 and 25 yards, both of which are well beyond normal self-defense scenario parameters. My thinking is that if it will group satisfactorily at 25 yards, it certainly will at 10 feet.

It also occurred to me that probably the most popular bullet weight in .45 ACP is still 230 grains. Therefore, I shot a group of 12 shots at 15 yards using Remington UMC 230-gr. FMJ ammunition to compare with the 160-gr. DPX using the same POA.

I did not do any rapid-fire with this load. The reason is that such measures only my ability with this N-frame S&W and may or may not translate meaningfully with either the skill of another shooter using the same or more compact handgun. In other words, I cannot accurately predict how much "combat accuracy" the load has for another. I can say that felt recoil was minimal and felt less than with the Remington ball, which averages 821 ft/sec from this revolver.

Chronograph Results: Ten shots were fired from the revolver to obtain the listed figures below. This was done with the muzzle 10' from the chronograph screens.

From the 5" S&W Model 625, Corbon's 160-gr. 45 AR DPX averaged 1108 ft/sec. The Extreme Spread was 37 with a Standard Deviation of 12. This would have been even closer were it not for the last two shots.

Here are the results for individual shots in feet per second:

Shot #1: 1099

Shot #2: 1100

Shot #3: 1104

Shot #4: 1102

Shot #5: 1098

Shot #6: 1107

Shot #7: 1111

Shot #8: 1105

Shot #9: 1122

Shot #10: 1135

This is very consistent ammunition.

Expansion Testing: As I've mentioned in previous articles, I do not have the money or the controlled environment to use calibrated 10% ballistic gelatin. I generally use two media for testing: water and "wetpack", which is merely super-saturated newsprint I've soaked for 24 hours and then drained 30 minutes prior to shooting.

Fired into water, this standard pressure load expanded every time. Five shots were fired.

Wetpack does not give as accurate estimations of penetration depths as does 10% ballistic gelatin, but Corbon advises that this bullet is designed to penetrated at least the 12" minimum recommended by the FBI. As a "control" I also fired a Winchester 230-gr. Ranger JHP (RA45T) to compare its penetration depth to the 160-gr. DPX. It has an average velocity of 869 ft/sec fired from the 5" S&W.

Ten rounds of 160-gr. DPX were fired into the saturated newsprint and the average penetration depth was 6.25". Ten Winchester Ranger rounds were fired and averaged 6.5" penetration. The Ranger law enforcement ammunition is praised by folks on various sides of the "stopping power" issue as being a consistent expander that can be counted upon to penetrate approximately 14" of 10% ballistic gelatin. Likewise, the Corbon DPX bullet expands consistently after passing through various intermediate barriers such as the dreaded 4-layers-of-denim test. It appears that it will penetrate at least the 12" demanded by most ammo-conscious users these days.

In the wetpack, the average expanded diameter of the Winchester Ranger was 0.75" x 0.73" x 0.462" tall and the bullets neither fragmented nor lost any measurable bullet weight.

Corbon 160-gr. DPX expanded to an average diameter of 0.73" x 0.71" x 0.475" tall.

Conclusion: For folks using the .45 ACP revolver for self-protection against felons, I believe that the Corbon 160-gr. load merits serious consideration. It will probably be used in lighter, more compact revolvers than what I used and with somewhat lower velocities. According to Corbon, this DPX bullet begins to expand at an impact velocity of 800 ft/sec. I can only guess here, but I'll bet that 3" velocities are in line with the 1050 ft/sec listed by the maker. The powder used is flash retardant and is reportedly optimized for use in shorter barrels. I expect velocity lost to be minimal and based on what I saw with the same load in ACP form, estimate it at between 950 and the listed nominal velocity.

(For those interested in the .45 ACP Compact Gun Load in the same bullet weight, follow the link below:

Earlier I mentioned that felt recoil was less. Putting a calculator to the bullet weights and their measured velocities from my revolver, the Corbon 160-gr. DPX auto rim round generates right at 7% less felt recoil than the Remington UMC 230-gr. FMJ. This should be easily controllable in a compact revolver.

There were no misfires or any problems at all with this ammunition.

Corbon 160-gr. 45 auto rim is intended for distances commensurate with the average deadly force scenario. The bullet is light for caliber and would not be well suited for use at extended distances as might be expected in hunting scenarios. It provides minimal recoil for quick repeat shots and being standard pressure, is easy on the smaller guns it might be used in. Flash retardant powder especially for use in short barrels gives the user all the advantages Corbon can. The ammunition is a consistent expander from what I've seen and capable of very fine accuracy.

Were I toting a small .45 ACP revolver, it would be loaded with this ammunition.

For information on this and other Corbon ammunition or questions, here is a link to their site:

Best.