LUse the XCB rifle Lamar. You've got a 14 twist on that baby. The differance between 12 and 14 would be very negligible for the purpose of seeing how much % of engraving you get on a reactive bullet. You should be able to get long distance accuracy with the 30SIL at 2600-2700ish FPS without working up too much of a sweat. Will it hold out to 500 yards? Good question.
Recon you could toss a few into something soft and post a picture? I can run some through my rifling die (it's like a Lee PT die but made out of a piece of rifle barrel) and we could do a little long distance comparisons here. We could do a couple other bullets too? I've got the 311466, the XCB bullet, and a couple old Lyman designs you might have also.
Whatcha say?