Hi I've just come across this discussion so sorry I'm late.
ive got 2 6mmbr's one rpa action and heavy 5r border barrel 1 in 8 twist for target shooting, which I had built about 12 years ago on Laurie Hollands recommendation.
the second is a nesika (very shiny and doesn't mark or tarnish) bought second hand from steve kershaw which I use for varminting.
you would have to wave an awful lot of cash under my nose to make me even start thinking about selling them. That's how impressed I am with the 6mmbr!
both guns are very accurate, not too fussy to load, loads of info and advice available on the web. You can't go wrong with this cartridge. The best of luck with your new rifle, you will love it!