U.M.C. Primer Diameters


U.M.C. Boxer primers come in 3 diameters.

A-No. 00-A quite small diameter primer

B-No 1, 1 1/2, 6, 6 1/2 & 10 all all the same diameter.

C-No. 2, 2 1/2, 7, 7 1/2, 8 1/2, 9, & 9 1/2 are all the same diameter.

I need to know the diameter of each of the 3 sizes in inches.

The same for Berdan #1, #1 1/2 and #2 primers.

The same for Wesson #1 & #2 primers. How can you tell a Wesson Primer from a Berdan?

The same for U.M.C. Colt’s Primer. This is not the same as the Colt’s Percussion Caps. This is, I think, a special size for Colt Pistol Cartridges.

Thanks for the help.



Here is the info I have…

A = .125"
B = .175"
C = .210"
#1 and 1-1/2 Berdan = .255"
#2 Berdan = .210"

Ron, I believe the Wesson primers were the .175" size, but I seem to remember they were of lesser height than the ones above. The Wesson primer is a Boxer type, not Berdan. I’ll try to do some more digging on this. I used to have tins of them, but not anymore.



Randy–Thanks a lot for the information. I need this information to illustrate the revised edition of my my U.M.C. CD. I would like a shaded line drawing of the Wesson #1 and #2 as well as the Colt’s Pistol Primer if possible. I have used nice drawings from the U.M.C. catalogs to illustrate all the other types of primers. I’ll use a B&W photo or scan if I need to, but a line drawing would be nicer if someone could find one.


Randy–When I went to add those diameters to the U.M.C. database, I see I missed 3 primers that I need the diameters of: #3, #33 and #5. These were all for shotshells. Do you know what their diameters were?


I was not aware that the Wesson primers came in more than one size. I have a UMC tin of these primers, but the labeling makes no mention of the size that I can make out through the rust stains. I have the patent drawing for the Wesson primer on the August 2005 picture page on my web site at oldammo.com/august05.htm if anyone has an interest.


I’m going from memory here–always a chancy business–but I think the primer UMC introduced as the Wesson, with no numerical identifer, later became the Wesson no. 0. It was a thinner version of the usual Winchester no. 1 (.175 in.) primer. Later UMC adopted the Winchester 1 and 2 Boxer-type primers (.175 and .210 respectively) and called them Wesson no. 1 and no. 2. Later the “Wesson” was dropped from their description. Jack


Guy–Thanks. Nice picture. Now we know one of the Wesson primers was 0.173 diameter, but which one. Here is a page from the 1 May 1882 U.M.C. catalog that lists the 2 sizes of the Wesson primer. In fact, it seems to indicate there are 3 sizes.


Jack–What you said sounds reasonable. Can you come up with any documentation. I really do not what to include your information in my U.M.C. CD based on a “if I remember correctly”.


Ron: I’ll look through my notes tonight, but maybe Guy can help sooner. I think that if any of the Wesson primers was .173 it was likely the first one that later carried the 0 designation. I think the 1 and 2 were interchangeable with the Winchester-type primers with those designations and thus .175 and .210. Jack
(p.s. on his web site I see Guy says the UMC no. 0 primer came out in 1883, so I believe that’s the date the Wesson without a number identifier became the UMC no. 0. It would have been a headache having Wesson no. 1 and Wesson no. 2 and just plain “Wesson” available for confused purchasers)


Jack–Thanks. I have tentatively added that information to the database with a “?” until we come up with some more documentation. BTW the way, I got the 0.173 diameter from Guy’s link from above.