#1). You can do this with a pocket knife... Couple hundred... your fingers will get tired, the knife will need sharpening, but... to prevent primer backing out and messing up in a full auto, the military has the ammo maker squeeze the brass into a small lip over the primer and even if the load fires "hot" it stays in... Little use among civilians.
#2). As indicated, there are no shortage, by all the major machine tool makers, of devices that force something in to "un squeeze" this lip... CH, I think, has one that screws into the top of the press for much greater ease of access. Busy work, but you only have to do it once and then you have some pretty good brass...
#3). You can use the "neck reaming" tool, as a rule. I have used the Lee tool enough to have gotten my fingers raw... No fun but works.
#4). If you are a hardware salesperson or a wood worker or
There is a bit for drills that cuts a taper (counter sink?) for flat headed screws, so the screw is "flush" with the surface. I don't recall the number(s) but there is one bit number for large primer pockets and another bit number for small primers. Chuck it in a spinner, drill, lathe, whatever... and with it spinning, touch the primer pocket to the cutter and the lip is cut away and a neat taper is cut, depending on your finger skill, to guide in the next primer... Many options. Dillion most expensive, probably good deal. For a few militarys, the pocket knife is plenty. Repeat, FEW... luck.
