49 Grain percussion primer

Looking for clean image of a 49 gr. percussion primer and it’s dimensions… USCCo or J.B Wise h/s would be a bonus. They both had contracts 1917-1920.


Scott, specimens and pictures of the 49 grain Mk I primer made by USCCo are hard to find. This is the only one I have taken from an old magazine:


Approx. dimensions are:

Case lenght: 54 mm
Rim diameter: 16 mm
Head diameter: 14 mm
Headstamp: U.S. 18 1425.310


When this thread began I wondered “what is a 49 grain percussion primer?” Learning via google it was a cannon primer I thought maybe I had one. What I have is headstamped U.S. above and at bottom 18 2872 - 280. Dimensions of .540 in. just below mouth crimp, .552 in. at head and .626 in. rim agree pretty closely with the picture shown, but the OA (per my notes) is 2 in., a bit shorter. Beneath the mouth crimp is a fiber wad. This then is a specimen? Jack

Fede, Thanks so much

Jack, Would you mind posting a photo or two ?

Scott: I’m unable to provide a photograph of the primer. I did double-check the length given in my earlier post, and it’s accurate. The headstamp is somewhat offcenter, so that the letters U.S. have only about 2/3 of their correct height. Thanks to you and Fede for the ID. Jack