The military semi autos (M1, M14/M1A, AR15, etc) don't have a firing pin return spring in the bolt to help keep the firing pin from hitting the primer when the bolt chambers the round. People are always asking about the little dent in the primer when a round is chambered and then ejected without being fired.
The military primers are supposed to be a little bit thicker/tougher and less likely to go off when that firing pin hits the primer.
I've never reloaded .30 carbine but I've loaded a truck load of .308, .30-06 and .223 for the above rifles using standard primers. Zero issues with any of them going bang when the rounds are chambered.
I have used the "military primers" twice (5,000 large and 5,000 small) years ago.
Oh, many people also recommend using the magnum primers if you can't find the military primers. They are also supposed to be thicker/harder cup material than standard primers. Just what I've read, can't say it's true.
Just looked at the Ram Shot and Hodgden powder reloading data. Both used small rifle primers for their load development. For what that's worth.