12mm Pinfire Cases with Short & Long Pins

I ask Aaron and others about these 12mm or .410 cartridges and their use.

The 12mm long pin cases I assume are for adaptors/reducers to shoot smaller calibres so the pin extends above the adaptor. I note that some adaptors have one and others have 2 pin slots.
I ask if the second slot at 6 o’clock causes the rim or base to blow out when fired?

The short pins I assume are for canne or walking stick firearms. I have two walking sticks but only certain cartridges would fit the chamber correctly These have no case rims. (see forum).

Third type is a 12mm and has a rim. I put a box of the ball short cased cartridges on this forum and it was marked as .410 1 1/4" case so for a rifle or .410 shotgun.
Has anyone seen a .410 pinfire shotgun or rifle?

I will not include individual headstamps as I hope to do an article for ACCA Journal.
I chose this forum first to get info and thoughts. Forum was getting a bit quiet on cartridges.
Feel free to add other photos of similar 12mm pinfires and I ask if I can use them in my article.


I have never seen an adapter with two slots. The only time I have used an adapter was to fire .410 centrefire cartridges in a 12 bore shotgun. The novelty quickly wears off because the extractor doesn’t work and it is awkward to get the fired case out of the adapter. Having two slots in the adapter might make it easier to grip the fired cartridge case and pull it out.

Come on Aaron. I am using your photo on your forum to ask a question.
I only have one brass adaptor 12ga/.410 with 2 slots. I thought it was only for centrefire shotshells but it can accept a rimmed cartridge as well as a rimless Pinfire.
I ask if the second slot causes the case to swell or try to fill this slot.
Are some adaptors for pinfires only with one slot. I do not know.

12mm Adaptors

I’ve really not seen much info on these adapters so I’m not sure of the exact reason for the two slots.

However I would not say that the long pins were only for use in these adapters. For instance, see the info on the cartridges I put here:

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