.30M2 brass
I've used military '06 cases since about 1962, used 'em to form 8x57, 7x57, 7.65x53, .285 OKH & others, all of which I also reloaded. Decapping is kind of a PITA, so have a few spare decapping pins available.
One system that has worked very well for me has been the Lee Loader decapper, with its punch, base, and mallet arrangement. It's a mite slow, but I've never broken one except by misuse (oops).
The RCBS Primer Pocket Swager works great, is adjustable for depth of swage, and produces a pocket virtually like commercial factory brass. Way better than reaming, IMHO. HTH
Larry