I suspect a .673 would be a better size.
I regularly use an Eigen .678 and it works well. The .005" step down would solve most people's roll out issues, without underboring too badly.
Thank you for a great product!
Oh... BTW, if you slip a Taso raincover over the porting, a Mini becomes silly quiet and a DM 9/10 becomes to quiet you can hear the bolt moving