Help on .41 Rimfire Cartridge Info

I got an email asking for some help tracking down some information on an old cartridge. I don't know the answer, but I'm sure one of you all out there will have the information they are looking for.

Here's the email:

"I am trying to find information on a .41 rimfire short cartridge that has a headstamp "P" (not raised). I believe this cartridge was manufactured by the Peters Manufacturing Company in the 1860's but I'm having a very hard time finding information."

If you have any info, please leave a comment, or drop me an email and I'll post it for you.

Thanks!