Update update-
So, after a LOT of measuring and borrowing a bore mic from work- basically I ran into a tolerance stack up issue.
Riley uses an undersized barrel that will bite into the jacket on a proper .311 bullet, but steel case tends to be undersized.
Combine that with a
Update- it may not be the ammo.
It may be the rifle.
Riley may be using .308 barrels for .311 bullets which would explain why steel case runs smoother in it because they tend to be .310 and lacquered along with crimping.