A couple of gents that I shoot with on a regular basis have 6mmBRs built on custom actions and they've allowed me to shoot their rifles.  Recoil is very minimal and their rifles are extremely accurate.  First time I shot one of the rifles at 100 yard target bullet hit dead center of a small bullseye.  Owner handed me another round to fire and I told him no thanks, I can't do any better than my first shot.   Not sure if either have done any varmit hunting with their BRs, but seem to remember a brief conversation about it being good for that and one of them was interested in having a 30BR built for deer hunting.  By the way, they do turn the necks of their brass as part of their reloading for extreme accuracy.