Midway sells both 6mm br and 7mm br brass so you either neck up or down depending on the parent case you choose. I know there is data out there, but don't remember where I saw it pretty sure it was in the pistol section of one the manuals out there. If I remember correctly it was a pretty popular loading in the XP100 and other bolt action type handguns.
Got curious and went to see if I remembered correctly. Both the Nosler and Sierra 5th Editions list data for the 6.5 BR. Nosler shows a high of 2753 fps with 100 gr bullets and a compressed charge of 33.5 AA 2460 and a high of 2529 fps with the 120 gr bullets and 31.5 gr AA2460 these were out of a 14" barrel. Could be fun in an ultralight walkaround gun. Hope this helps.
