357 Atomic Ctg

I recently saw a 1957 ad for Great Western revolvers. One of the listed calibres was 357 Atomic. What was this cartridge?

The number one Google result shows a forum with one member saying this:
“it’s a trade name cartridge and is a 357 Mag loaded to +P; at 2400fps with a 158 pill in a regular .357 Mag case.”

Wow on the 2400fps, I didn’t realize that was possible with a 158gr bullet in a .357mag loading, unless they are talking from a lever-action carbine.

At what barrel length?

The designation only represents using 16.0 grains of 2400 and a 158 grain bullet in the .357 Magnum.



Oh sorry, I see now that it implies “2400 Alliant” powder, and is not talking about velocity, I think. In any case, it’s a hot .357mag.

Yes! I think shooting that could be a bit stiff! Well my old Speer manual has a max load of 2400 at 15.9 gr at 1335 FPS.??

Looks like it was a hot loaded 357 Magnum. Thanks for the replies.

An article pushished in 1957 says: "Bill Wilson, chief guru at Great Western, contributed a 7 1/2 inch 357 for the cartridge he likes to call the “Atomic”… “I tried some of the so-called 357 Atomic loads of Bill Wilson’s, 14.7 grains of #2400 powder”… “The Wilson bullet is the flatnosed 165-grain all lead”.

There is also contradictory information in very early sources, like a Hy Hunter advertisment from 1954 which says: “.357 Atomic (a company innovation employing a longer cartridge than the .357 Magnum)”.

‘Longer cartridge’ might simply mean that they did not seat the projectile as far into the case as a normal 357 Magnum load - therefore longer cartridge but same length case. Maybe this was needed to fit the heavier powder load without compressing it? Not sure how full the case would be with the mentioned ‘atomic load’ though.

Back in the 1980’s Federal used to load a 180 JHP .357. I shot up many boxes of those, I don’t know if they still load that or not.

Note; I just looked it up and they still do, along with several other company’s

There’s also a .375 Atomic, that is a 30/30 or a 375 Win case cut down to 1.40". Very similar to the 375 Super magnum, only shorter

I also remember seeing, in the 1950s, the Great Western revolver magazine ads listing the .357 Atomic as one available caliber of several. They sold for about $100, quite a sum in the mid-50s, so they were not cheaply made. The very first issue of Guns Magazine in January 1955 had a picture of a cased pair of Great Western revolvers on its cover. It was the first of the Colt SAA clones or replicas, as Colt had ceased production of its SAA prior to WWII. The postwar popularity of western movies and TV shows created a great interest in and demand for such SA revolvers in the mid-1950s and so the GW revolver came on the scene in the mid-1950s. In fact, many Hollywood productions used Great Western revolvers instead of Colts. They used to be fairly commonly encountered, but I haven’t seen one in many years, and I have never seen one marked as being chambered for the .357 Atomic, as shown. I always thought that the .357 Atomic was just a sexier sales-boosting name for the .357 Magnum, and not a different cartridge, as in the 1950s the subject of atomic weapons was a popular area of discussion. It probably referred more to the revolver as chambered for the .357 Magnum than to a cartridge.

This is the quote from John Taffin’s article: “A few weeks later I traded into a fifth Great Western, a five and one-half inch .357 Atomic. I believe the Atomic was a +P+ .357 load that resurrected the original .357 Magnum loading of 1935. That old loading was 16.0 grains of #2400 behind a 158 grain bullet and is not to be used in any of today’s .357 Magnums that were not specifically designed for it.” The operative phrase is highlighted. There is no indication that it was factory loaded or supplied in that form by anyone, or that Taffin ever even fired a .357 Atomic cartridge. Therefore, I tend to believe it was a handle applied to the standard .357 Magnum cartridge of the time by GW for sales promotion purposes.

I’ve found information on the true identity of the .357 Atomic:

1955 advertisement:

I am resurrecting this old thread because I was looking through my latest edition of the Blue Book of Gun Values today. It has a fairly comprehensive treatment of the Great Western revolvers in different models. However, it does not specifically state that any GW models were actually chambered for .357 Atomic. It does mention .357 Atomic as being a proprietary cartridge in a detailed historical background treatment, but provides nothing more than a mention (A picture above shows that some GW revolvers are known that had the .357 Atomic caliber marking).

It did say one thing I had not known, that some early GWs were built up using surplus Colt parts, as Colt had stopped production of the Model P prior to WWII.

So, has anyone seen a box marked as containing .357 Atomic ammunition, a product listing for .357 Atomic ammunition, or even a single cartridge that was so-headstamped?

Dennis, I’ve found this information in a Great Western catalog of 1955. Anyway, I think it brings more questions than answers but the .357 Atomic and Magnum are clearly differenciated. They also list a “.44 Special (our own extra high velocity load)”!!!

It seems strange that they show only Remington-branded cartridge boxes of standard calibers. I would have thought that had they offered the .357 Atomic, they might show a box of it also. The cartridge representations show only what appears to be a .357 Magnum cartridge, and if the Atomic existed at at all, it is suggested as being dimensionally identical to the .357 Magnum cartridge, i.e., there is no photo of a longer version of the .357 Magnum provided. I would guess the ,44 S&W Special with their own “Extra High Velocity Load,” again if it was sold by them at all, was probably a handload using one of Elmer Keith’s famously hot recipes for the .44 Special that pre-dated the introduction of the .44 Magnum (which is not shown as being among their cartridge caliber offerings of that time).

I continue to believe that the .357 Atomic was more or less a myth perpetrated for publicity purposes, absent a sample of a headstamped cartridge, a cartridge box, or anything else of a substantial evidential nature apart from their own advertising copy.