I can't help with the "R" meaning. Mine is #101XXX, and is all matching with a minty bore. Shoots much better than I can hold. It swallows the Winchester White box stuff with no failures, but does not like my reloads. Apparently my crimp is not strong enough to hold the bullet and after just a few rounds the projectile will be separated from the case, spilling powder and jamming. This same ammo runs fine through my P08's with no issues.
Woody
|