I discovered another serious issue not presented in hardly any of the essays about loading for service rifle.
I use a mild load, all the bullet has to do is punch a hole in paper after all, and I've been using the RCBS X-Die which eliminates the need to trim cases, vastly extending case life.
The problem is, and it wasn't only with X-die sized brass is my primers just weren't seating deep enough. I figured my Lee hand primer had worn out but when I got the Dillon, the same thing occurred so I researched the issue. It turns out the primer pocket thickens! Every firing makes it shallower than it was before! The cure is a primer pocket uniformer sold by Sinclair or Lyman. I picked up one from Bass Pro Shops, it's basically an end mill with a stop collar to machine the pocket to uniform depth. I'd always known they were used by the benchrest crowd to get everything exactly the same, but hadn't realized service rifle loaders need them too. After uniforming, primers are .004" below flush.
I took mine out of the handle and chucked it in a drill and found out my pockets were so thick the tool's teeth would fill with brass and it wouldn't cut deep enough. I pull it out a time or two, clearing the chips out and it seats against the collar like it's supposed to.