Here's why:
That little indented ring around the primer is the crimp. Most military ammo has crimped and sealed primers; and while they serve a useful purpose for the military, for reloaders they make things.. a little more difficult shall we say.
The best way to deal with crimped primers is to have a single stage press set up with a decap only die. That way you can just continuously decap the cases without any of the effort of resizing applied at the same time; because crimped primers can take a lot more effort to pop out, especially if they are sealed.
That leaves you with a decapped case that still has a crimp ring in the primer pocket. If you try and prime cases without removing that crimp ring, a number of things can happen. The best possible outcome is that the primers require a hell of a lot of force to seat. The worst is that the primers deform horribly on seating, ruining the case, jamming up the press, and possibly igniting (I've had all but the ignition part happen).
So let's not try that then OK.
Theres a tool called a crimp swager, that in one quick step presses out the crimp, re-swaging the primer pocket. It also needs to be set up in a single stage press; unless you get one of the free standing models that bolts to your bench.
Unfortunately, I don't have any of my single stages set up at the moment, I don't have a primer pocket swager; and I had 300 military cases to reload yesterday.
The other solution, is to ream the crimp out with a primer pocket reamer, which I DO have. Of course that's a hand operation, and you cant just ream the crimp off, you also need to clean and uniform the primer pocket and clean up the flash hole (actually you should do that on military, and a lot of commercial brass anyway).
At least I've got one of the RCBS time mate centers; because doing itcompletely by hand... well let's just say I wouldn't have made it through 50 rounds.
So what I did was, I took my Hornady .223 dies, which have a very long decapping stem; and I backed it out far enough that it was acting as a decapping and neck expanding die only. Then I set up my RCBS small base die to work the case; and I ran them through the progressive with just those two dies running.
Even then, the force required to cycle the press was.. substantial.
From there, I manually reamed every primer pocket, cleaned up the pocket and flash hole, and if necessary reamed and deburred the case neck; taking about 15 seconds per case. The whole process of prepping those 300 cases took me four hours; and that wasn't even loading them, it was just getting them ready to be loaded.
Let me tell you, 4 hours of grasping small, slightly slippery objects, and applying them precisely, and with force, onto tool small rotating heads... Well when I woke up this morning my hands were extremely unhappy, lets just say that.
Thankfully of course, once those steps were done it was easy to complete the job of loading; and it went through near as fast as pistol ammo.
Now tomorrow, 300 more of my match grade. I'm using Winchester brass on those, so thankfully no more primer pocket reaming. It's still going to be "fun" though, since I individually weigh each charge. Should take me pretty much all day. Good thing I can do it in between teleconferences... or for that matter DURING some of them.
