COTW shows that both the 22WCF and the .22-15-60 Stevens have a rim diameter of 0.342".
But the base diameter of the 22WCF is listed at 0.295", while the base dia of the .22-15-60 Stevens is listed at 0.265".

Campbells book on The Winchester Single-Shot contains a footnote on page 97 that states " (1) The Winchester Single-Shot is simply another name for the 22 WCF. The listing is included here in case any " .22 SS " caliber stampings are encountered. " 

The 22-15-60 Case is just shy of being 3 inches in length so it would be some what easy to rule in or out by just looking down the chamber.

Farther reading in my old (1926?) Ideal book says that 22636 and -37 in various weights are for .22-15-60 Stevens Straight, .228 are for 22-10-45, .22Extra Long C. F., 22-13-45 Winchester, and .22 Savage High Power.  And that 22636 and -37 and -38 hollow point can be sized .26 or .28.  Finding any of these molds in the outback would be like finding a diamond ring on the sidewalk in a Mexican border town.  I think the s s  means Stevens Straight.

Stevens seems to have had a fetish for the longest, skinniest cartridges possible.  Good luck.

James

I've long believed that Winchester used the letters SS to cover for the fact that they were chambering for a competitor's cartridge.   

One or two Stevens catalogs touted as an advantage to the .25-21 that because the inside of the shell was straight, you could load lesser charges.  By implication the shooter would push the bullet down on the overpowder wad to avoid airspace.  I have a .25-21, but I don't use black powder, so have never had occasion to try it.

Looking at the J Stevens Catalog No. 50, in the cartridge description section, it's interesting to note that the catalog illustrations of the long straight cigarillo shaped .22-15-60 (introduced in 1896 according to the catalog), .25-21-86, .25-25, and the .28-30-120 cartridges all having the word STEVENS suffixed onto their respective catalog cuts, but the bottlenecked 25-20 carries the suffix CENTRAL FIRE without the STEVENS.
I’ve often wondered if this seeming discrepancy in the catalog was due to the earlier Maynard’s having chambered the bottlenecked 25-20 single shot cartridge.
I have seen Stevens rifles chambered for the 22-15-60 cartridge having the 22-15 SS barrel marking.

In the WRA catalogs issued in 1886, the model 1885 rifle section lists the .22 WCF as one of the available chamberings, but when you go to the ammunition section of those same catalogs, the catalog cut shows the cartridge listed as the .22 WINCHESTER SINGLE SHOT ,  not as the .22 WCF.
Those WRA catalogs show the .22 WINCHESTER SINGLE SHOT cartridge loaded with 15 grains of black powder and a 45 grain lead bullet, so it might have also been called the .22-15-45 cartridge, or maybe the .22-15 SS cartridge. 
In 1890, WRA shows the .22 WINCHESTER SINGLE SHOT cartridge was now loaded with 13 grains of black powder and a 45 grain lead bullet, so it could then have been called the .22-13-45 cartridge, or maybe the .22-13 SS cartridge. 
In 1896, Stevens says they introduced their straight walled .22-15 SS cartridge.
The WRA catalogs, in the ammunition section, continue to show the .22 WINCHESTER SINGLE SHOT cartridge up to and including Catalogue No. 78, dated Jan 1913.
In 1914, WRA Catalogue No. 79, in the ammunition section, the catalog cut shows the .22 WINCHESTER CENTER FIRE cartridge.

@BP - I've taken that designation of the .25-20 Central Fire as being meant to distinguish from the already popular .25 Stevens rimfire, but it could just as well be an admission that it wasn't one of their proprietary cartridges.

OTOH, somewhere in my hard drive, however, is a photo of an antique ammunition box clearly labeled .25-20 Stevens.  So at some point they did try to claim it, apparently.   

(I'm about to drop off, so won't go looking tonight.)

Phil

uscra112 wrote on Feb 27^th, 2017 at 11:14pm:


No doubt about that!  That's clearly the implied claim in their catalog description of the cartridge. And after 1890, Maynard (Mass. Arms) could not protest--it was defunct.