Cartridge ID?

Anybody wanna take a guess what this cartridge is? On the left, with a 308 Winchester for comparison.

Apparantly from the 1950s or 1960s. From Winchester. No headstamp. Silvertip bullet.

CL = 2.012"
Rim diameter = .528"
Base diameter = .522"
Shoulder diameter = .475"
Length to shoulder = 1.560"

A prototype for a Winchester Short Magnum? What?


Bullet diameter? JG

Sorry. How could I have been so . . . what’s the word I’m looking for - nonretentive?

30 caliber.


A wildcat made from some exotic cartridge?It has the same base diameter as the 8 x 68 S.Are there some signs left by a lathe or other tools?

The measurments you give seem to be compatible with measurements I have for a Winchester experimental cartridge, called by one collector “.308 Winchester Mag “Fat” case.” The bullet is a standard “Silvertip.” These rounds were not headstamped, and have a nickeled-cup primer. Dimensions I have are as follows:

Rim: 0.529"
Head: 0.522"
Shoulder: 0.474"
Neck: 0.338"
Bullet: 0.308"
Case length: 2.08"
Ctg. OAL: 2.786"
Ctg. OA Wgt: 407.2 grains

Any differences between your round and these measurements seem to be insignificant. I do not have the head to shoulder length measurement.

Reference: Otto Witt

I bet Winchester would have loved to have been reminded of these back when gunwriter Rick Jamison took them to the cleaners circa 2005/2006 over infringing his short magnum patents.


That’s the same cartridge. Otto and I have talked about it and he does not have an ID either. I told him I would ask on the Forum and I also sent a photo and description to Chris P to post in the JOURNAL.

I think I know where that particular name came from. It’s not official, just a name used to describe it, for lack of anything else.

I think it was probably a prototype by Winchester for a new magnum cartridge that never happened. That is, never happened until 2000 and the 300 WSM.

I have prototype cartridges, unheadstamped, for this cartridge, the 6mm W (243W), 30-80WCF (308W), the 307W, and the 356W.


No, it’s not a wildcat. It’s a factory cartridge.


What sort of dates would we be talking about?

I can’t see why Winchester would consider a design so visually close to the .308 either on the grounds of safety or marketing edge so I guess it must pre-date the .308?


I can’t really put a date on it. The primer, base style, color of the brass, etc seem to be close to the prototypes that I have of the 30-80WCF, 6mm Winchester and 358 Winchester, so I’d lean toward that period - 1950s & 1960s. Also, the Silvertip bullet has the same general “look” as bullets from those years which could be another indicator.

I have seen nothing to indicate that Winchester was contemplating new cartridges based on any cases other than the T65 and the belted magnums immediately before or after the introduction of the 308W. If they were, they kept it a well guarded secret.

On the other hand, the short & fat craze didn’t begin until the 1980s & 90s and the cartridges by Winchester and Remington weren’t fully developed until the turn of the century so it would seem odd if this cartridge was a prototype that laid dormant for 30 or 40 years.

This is all pure speculation, I know, but you have to start somewhere. I posted the photo here and in the JOURNAL hoping someone would recognize it.


I was just thinking out loud really. Winchester, like all companies, exist in a consumer driven world where fashions come and go and I couldn’t really see where they thought this cartridge was going to fit in to an already crowded market place.
Maybe thats why it never happened. Perhaps it was displaced by the arrival of the 7.62/308 which came in from an entirely different set of circumstances and was virtually guranteed commercial success.

My initial thought was that any rifle chambered for the prototype looks like it could potentially also take and fire the .308W cartridge (which would then probably rupture. )
Or the reverse situation where a hunter drives for days to his cabin in the woods only to find his cartridges are too fat to fit in his rifle.

Having two virtually identical .308 Winchester rounds on the same shelf would have led to endless mix ups and confusion.

Anyway its a very interesting cartridge and thank you for sharing it with us.

Vince - while I agree with every point you made completely, the factories have never been deterred by an over-crowded market. Look at the sporting- rifle cartridge situation right now, with the cartridge of the week situation. I don’t know how guys keep up with them all. If we eliminated 95% of all the cartridges ever devleoped and produced, there would still be no wild game or domestic animal (including criminals) that could not be effectively taken, no military combat requirement that could not be satisfied, nor any shooting sport that could not be taken or fulfilled perfectly.

Of course, it wouldn’t be as much fun for the cartridge collector!

One of the worst examples of the overcrowded marketplace is a subject close to my own heart - the London Gunmakers.
Each gunmaker had their own range of calibres purely to convey the illusion of being bespoke and unique.
Often only a few dozen rifles were made in a particular calibre and meant that many good rifles ended up as curiosities long before they should have.

However, like you say for us its wonderful.