.37 Winchester Experimental Rimfire?

Hello to everyone!

About a year ago I had acquired a similar cartridge to this one (not this exact cartridge shown below), and have been trying to do research on it ever since.

The only information I can really find is on gunauction.com at the following link:

I must add, the head of this cartridge has no headstamp.

I know there are very knowledgable collectors in the IAA, and before emailing Winchester to ask for their opinion on it, I figured I would ask the IAA community first.

Any thoughts are welcome and appreciated!

Hi Rimpin.

Dick’s description is pretty accurate. I don’t know about the date. I thought it was 10 or 20 years earlier, but will deffer to Dick (Fraser) on this one. The rounds are scarce but not rare. I have had a couple of boxes over the years too. Again not rare but scarce. The other variations are New Primed empty and a dummy using a snapped case, with a very small hole in the side and another in the middle of the base.

Sorry, but that’s the extent of my less than meagre knowledge on this one.


Could this be a US(WRA) equivalent of the European 9mm Flobert RF shot cartridge?

.37" is close enough to the “9mm” specs to be similar, if not interchangeable with, the Paper cased Flobert shot cartridge.

Just a query given the visual and dimensional similarity.

Did WRA make any .37 RF shotguns? ( ie, single shot, bolt actions or similar)? or was it a Cartridge-only project to fill a Market void for Flobert shot cartridges and imported Guns?

Doc AV

Powdertin: If you have photos of the variations available, I wouldn’t mind taking a look. But if not, no worries. I didn’t know there were other variations out there!

DocAV: I am not aware of any .37 cal firearm. I did check the measurements of my 9mm paper Floberts (including paper 9mm Winchester shot), and the measurements were anywhere from 8.70mm-8.90mm. The measurement of this .37 Winchester is exactly 9.40mm (which is 0.370")

What I am not aware of is, what the maximum chamber size of a “9mm” rimfire can be? Because technically, if the cartridge is too wide, it just won’t fit…

Thank you to the both of you thus far for some responses!

The only reference I have in my files is a quote from the New Zealand Club’s bulletin of Oct/Nov 1993 wherein in states that this experimental cartridge was made for an experimental re-chambered Winchester Model 37 top-break shotgun. No factory data ever released and all reports were prepared for internal use only. No indication as to what internal report might still exist. It also dates it to circa 1937 but I don’t know how they arrived at the date except that it used the Model 37 shotgun as part of the development.

That is interesting to know, thank you for that info!

The year does coincide with the Winchester Model 37, but I wonder why they chose that model…

Could it have just been a flopped attempt by Winchester, and they didn’t want to inform the public about their blunder?

One very interesting cartridge none-the-less!

For what is worth, Barber p. 95 mentions: “By 1965 experiment #3,141 had been logged for the .37 rim fire shot case”. Also, in p. 210 it is described as “experimental 1967”. The source of this information is not specified.

Was perhaps this mini shotshell a contemporary to the Remington .310 Skeet cartridge? It would seem Remington went pretty far with their project based on the remaining amounts of .310 cartridges and it would not surprise me that Winchester at least toyed with marketing a similar item. Or perhaps Remington was following Winchester’s lead?

Winchester also produced the 5mm Wingo rimfire shot cartridges for gallery use in a venue that never took off.


Does Barber mention a description of the .37 rimfire (i.e.: Brass case, rolled crimp and/or top wad)?

You could be on to something there… It basically looks like a similar design to the .310 Skeet cartridge, only the .37 has a top-wad instead of a plastic disc.

According to “The History of Remington Firearms By Roy Marcot”, the .310 Remington Skeet was produced in “The early-1960’s”… On that same note, Fede’s post regarding Barber’s publication mentions the years 1965-1967. It could be possible that Winchester was trying to improve on Remington’s cartridge, but didn’t document anything on the .37 due to copyright infringements? (It’s just a thought)

Th story I heard was that it was the result of Remington’s work with the .310 rimfire shot. I don’t rememder who told me this for sure but I think it might have been John Barber. I have no first hand data to support this.


Thank you to everyone for their input on this one.