The $5 Solution.
LINK:
http://www.harborfreight.com/3-in-1-hex-bit-countersink-tool-68535.html
The same counter sink (better quality/no handle) is sold at Sears & Wally-World for about $10
A hand drill with speed control makes this about a 1,000 Round an hour tool.
I just cut 4,000 Military rounds in about 4 hours with the countersink in a hand drill.
Not a bad deal for something you do ONCE to the brass,
Nothing screwed to your bench in the way, taking up bench top space, and didn't cost $100+ you could have spent on other stuff you need more...
No more grunting, No more akward angles, no more hammering on stuck swaging tools,
$90+ back in your pocket...
Once the hardened lip is gone, you get a nice FUNNEL to guide your new primer into the pocket,
As long as you don't cut any farther than the rounded edge of the primer cup, you HAVE NOT effected the ability of the case to hold the primer (as some have suggested)...
It's literally a one second operation with a hand drill, three seconds by hand.