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The Ultimate Reloading Manual
Wolfe Publishing Group
  • reloading manual
  • alliant reloading data
  • reloading brass
  • shotshell reloading
  • bullet reloading
The Ultimate Reloading Manual
load development

.41 Avenger

Author: Russ Gaertner / Wolfe Publishing Co.
Date: Mar 01 2012

The .41 Avenger is a wildcat cartridge for use in .45 semiauto pistols. Developed by J.D. Jones, the well-respected firearms designer and customizer, gun writer, and president of SSK Industries, the .41 Avenger is capable of producing at least 30 percent greater muzzle energies than .45 ACP. It combines the stopping power of a big bore with the better ballistics of lesser calibers. Recoil energies are reduced and manageability is improved by use of lighter, 410 inch bullets at higher velocities.

Conversion of a .45 auto pistol, or a Commander, to .41 Avenger is easily accomplished with a kit marketed by SSK. The kit contains a match-grade barrel with fitted barrel bushing and link, a set of Pacific reloading dies, a set of heavy duty gun springs and handloading data.

After receiving the oversized barrel made for fitting by a gunsmith, I installed it in the slide/frame of the old model Colt Gold Cup .45 used in my earlier .45 ACP accuracy work (Handloader No. 951, in order to make possible a direct comparison between the two calibers. The fitting was easily accomplished, but it later became evident that the fit changed after extensive firing. A “drop-in” barrel can also be ordered from SSK and requires little or no fitting,

Initially the gun was evaluated by making up five to ten rounds each of over thirty different loads listed in the SSK data sheets and firing them in five-shot groups from the Lee pistol machine rest, clocking velocities with the Oehler Model 33 Chronotach. Many of these groups were exceptionally tight and most of the loads were hotter than indicated by the SSK data. Some listed loads were definitely over-pressured in my gun.

With the publication of my .41 Avenger review (American Handgunner, Jan.-Feb. 19831, I decided to pin down the fine performance of the caliber by more extensive handloading and testing. The accuracy potential was of special interest.

Handloading Considerations

The .41 Avenger is strictly a handloading proposition, of course, and the brass must be formed by the handloader. Several types of .45 brass can be necked down by running well-lubricated cases into the sizing die supplied with the SSK kit. No fireforming is needed.

The .45 ACP brass yields .41 Avenger cases which are about, 898 inch long. Though shorter than the chamber (cut for brass, 950 inch long), they work effectively and are much cheaper than other cases. Headspacing is on the shoulder, not the mouth, so length is not critical. The sizing die was adjusted and locked in my Redding Model 25 turret press to provide about, 005 headspace in my gun.

SSK instructions state that .45 ACP cases should not be used for heavy loads, because the pistol brass might blow out around the unsupported groove area with high pressures. They suggest the use of stronger brass formed from, 451 Detonics Magnum cases (no other modification needed), or from reamed and trimmed, 308 rifle brass, or from .45 Winchester Magnum cases, which must be shortened, formed and trimmed. I chose the last route, and I have reloaded both these and the .45 ACP type fifteen to twenty times with no loss due to normal loading and firing. No neck annealing has been done to date. A roll crimp may be used, but I prefer a light taper crimp, easily obtained using my RCBS Carbo sizing die in .41 Magnum.


The performance and advantages of .41 Avenger are best realized with 170 to 185-grain bullets. However, some 200 to 220-grain slugs shoot very well, though recoil is more noticeable and some designs do not feed from the magazine reliably. For reliable feeding a round or smoothly tapered bullet nose is best; wadcutters and semi-wadcutters are generally unsuitable.

The Sierra jacketed hollow cavity design is ideal for the .41, and most of my loads involved the 170-grain and 210-grain JHCs, which are identical except for length. The cast .41 slugs available to me were not reliable, but NE1 moulds were provided by SSK Industries for two new J.D. Jones designs – a truncated cone (flat-nose) and a round-nose, both with a faint crimping shoulder and a single lube groove. These performed faultlessly. Both were 185-grainers nominally, weighing less in linotype. Lawrence Magnum alloy was used for full-weight bullets. The RCBS Lubrisizer with RCBS Lube and a .410 inch die was used with appropriate nose punches. Finished bullets were inspected for complete fill, but not sorted by weight.

ACP brass with three headstamps was used: W-W, R-P, and Federal. The uncannelured cases were preferred because in the .41 Avenger the cannelure is located in or near the shoulder, weakening it. If a roll crimp was applied with the seat/crimp die in the kit, the shoulder showed a tendency to bulge, requiring full-length resizing of the loaded round (not recommended). This was not a problem if a light roll crimp was used, but length variations gave a non-uniform crimp. Therefore, the taper crimp with the carbide die was used on all of the accuracy loads, which also appeared to feed smoothly.

Most of the light and medium loads were made with CCI No. 350 (magnum) primers. For medium-to-heavy loads, harder W-W 7M magnum large pistol primers were used. The heaviest loads, including all of those with Blue Dot, were primed with CCI No. 200 large rifle caps. The harder cups of rifle primers were desirable to minimize primer cratering and extrusion into the firing pin hole. If this occurred, the extruded metal was shaved off in part, showing the brass in the cup. This never resulted in piercing or leakage of gases from the round, but the firing pin hole in my gun is close-fitting. In a looser fit between pin and hole, this might lead to a dangerous leakage. In heavy load firing, the use of a heavy duty firing pin spring and hammer spring is recommended for this reason, also. My gun was reliable with all of these primers.

During all firing, a Wilson Shok-Buff composition buffer was kept in place on the spring guide and a heavy duty recoil spring was added for heavy loads. These served to prevent damage due to metal-to-metal contact and peening in recoil. Even so, the heaviest loads caused some detectable marks on the base of the spring guide and on the link mounting stud. After all testing had been completed, the Gold Cup barrel was replaced in the gun and several groups were fired for accuracy. It was shown that little, if any, loss of .45 accuracy had resulted.

In addition to those listed in the SSK data, a number of powders were tested briefly. However, the full range of loads could be made with Bullseye, 231, and Blue Dot, and no other powder was found to be as good as one of these three for any need. Unique, while usable and good in some loads, was not as uniform or clean-burning.

Accuracy Firing

Series of loads differing by .2, .3 or .5-grain increments of powder were prepared and fired in a single session. Duplicate series were prepared and fired in separate sessions at the range. Each powder charge in these series was weighed with a precision of less than k.05 grain; charges thrown by my Lyman-Ohaus Duo measure seemed to give similar velocity spreads in a few checks. In addition loads were checked for functioning through the magazine, since the gun must be single-loaded in the Lee rest. The best length range for feeding was 1.20 to 1.26 inches, so all bullets were seated to 1.24 OAL, and crimped separately with the .41 Mag RCBS Carbo sizing die.

After each five-shot group, the chamber and bore were checked for leading and residues, and cleaned with a dry brass brush if dirty. The gun was cleaned between sessions, but most of the loads were very clean burning. Fired cases were checked also for primer pressure signs and for other signs, including bulging in or near the extraction groove (none found). Average velocities and standard deviations were recorded from the Oehler Model 33 readout. Groups were printed on reversed full targets at twenty-five yards, usually nine or more groups per sheet. They were measured center-to-center of widest hits with a micrometer caliper and recorded. Three or more groups were fired for each load and averaged. Only a few obvious fliers were omitted. Most firings were done at 60 to 90 degrees, and slowly to keep the gun cool.

Results obtained early in the testing, but after initial work reported elsewhere, included the best groups, then they began to open noticeably. This was traced to “wearing in” of the barrel, with resulting slight binding of the barrel extension or tang against the left side of the slide and of the link in its mounting. This was relieved by filing and polishing the side of the tang and the inside of the slot holding the link. Groups improved but did not tighten up to the .original excellence.

To illustrate this effect, Table I summarizes the results of eight series firings, all in .45 ACP-based brass (Federal, W-W and R-PI with CCI No. 350 primers, Bullseye, and the cast (Magnum alloy) 186-grain, truncated cone (TCI Jones bullet. These series were run over a period of more than three months, and the first series was the best I have ever fired (or heard of) by any regular handgun in a centerfire caliber. The ten groups in series 1 ranged from .78 to 1.21 inches, averaging just 1.01. (Actually series 1 also included three other loads - 3.4, 3.6 and 3.8 grains, all under one inch - which did not cycle the action reliably.) Series 2, 3 and 4 were fired as slight binding developed, and some heavy firing was also done during this period. Series 5, 6, 7 and 8 show the improvement after refitting.

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