Gunshow find - unknown

Yesterday at the Edmonton gunshow I was given these items with the hopes of identifying them. They are loaded with powder. The headstamps of the .22 inserts are ‘U’ and ‘H’ (in a circle), respectively.



They look like part of some piston-driven tool. Can you show a pic of the end opposite the headstamps?

Hello Paul,

Just throwing the idea out there, but can they be some sort of fabricated adapter to convert a firearm into a .22?

Here is an example on as to what I am referring to:

Very interesting regardless.

RimPin - Auxilliary cartridges are a well-known subject, with most such adaptors having the shape of the chamber they are to fit in - in most cases that basically means they have the shape of the cartridge case for the original caliber of the firearm in which it is uses. The one you supplied the link to is an example of that - it is the shape of a 12 Gauge shotgun shell, including rim. Then, they are chambered for whatever small cartridge is desired to be used with them. I have a 12 gauge adaptor much like the one pictured on the link, except it is blue, and is chambered for the 9 mm Para (Luger) cartridge and has a rifle bore ahead of the 9 mm chamber.

The ones Paul acquired do not seem to have the shape of any firearms chamber (and cartridge case), or at least none with which I am familiar.
That lends some credence to the fact that they may well be for some sort of tool, like a stud-driver.

As Jonny pointed out, a picture of the other end of the cartridge, and menition the internal chamber and bore, if any of the latter. For instance, if the holes for the .22 blanks goes thru to the other end, is the other end threaded? Some tool adaptors are.

Whatever they are, they are interesting!

Paul, are they steel, aluminum…?

Sorry for the delay…

Aluminum and nothing to be learned from the topview - just machining marks.


Are we sure the cartridges are actually supposed to be in those, or do they just coincidentally happen to fit?
Do you know if they are ball or blank cartridges?
How would the cartridges be removed or replaced, or is this a one time use device?

Looks like the recessed area leading to the cartridge base are deeply cut more or less dome shaped, so any sort of “firing pin” would have to be centered at the presumably dome or pointed object that would fit into the recess.

There seems to be some carbon in the dome of the larger one, suggesting perhaps use in some sort of internal combustion engine? Or perhaps in some sort of metal forming process where material is forced into the dome, impacts the cartridge and the resulting pressure forces it back out?

Another point is these being rimfire 22’s the firing pin for the initiator would have to be off-set & not central, where as the shot shell auxiliary / adaptor RimPin noted has the 22 off-center so the central firing pin will strike the rim.

An x-ray?

Is the end opposite the cartridge end removable? Appears to be a seam there, or does this slide out? Curious item.

I am wondering if these are some sort of reloadable case for a flare or sky-burst popper for a perimeter-defense trip-wire unit, of the sort sold commercially to the survivalist market like these (or something like this one, there are many):

If the top unscrews it may just be a cover for storage, and then either a loud report device, or flare could be inserted, with the alarm having a spring-loaded pin hitting the primer to activate it. I don’t, however know why a .22 would be used in this way, centered instead of offset. Most of these trip-wire units are made to trigger a centerfire cartridge such as a 12ga, or a .308, .38spl, or 9mm blank. Many of these devices come & go in small runs, or are machined by one seller only and will disappear after a short time, much in the same way as the 37mm & 26.5mm adapter devices will, which are all custom machined on short production runs.