I’ve shot a lot of 10mm. Probably not a lot compared to, say, the FBI, but quite a bit of it. I’m also familiar with the story of the development of the round, as well as it’s shorter brother, 40 S&W. The 10mm utilizes a large pistol primer, much like the 45ACP.

When I was sorting and measuring the 10mm brass, I stumbled across a few cases with small primer pockets.

Note the “NT” on the headstamp. Turns out that Federal Cartridge makes the a line of non-toxic ammo. Seems counter intuitive to think of non-toxic pistol ammo, but they mean non-toxic to the shooter, especially frequent indoor range shooters. Lead free (or at least completely encased) bullets, powders, primers, etc. I’m not sure what the small primer advantage is, especially since the product webpage above indicates that the round uses Federal 150 primers, which are large pistol primers. Shrug.

There is also some discussion on the ‘net about manufacturers finding that with today’s primer and powder chemistry, there is no particular advantage to large primers. If you have to buy a few million of two sizes when could get by with a few more million of one size, it starts to make monetary sense.

Once I got through all the brass, there was just barely short of 1 box of these particular cases. I’m gonna load’em.

Note that the small primer was crimped in. I will need to ream the primer pocket, but I have the technology.