I would like to know about the twist rate, although the 196gr. Sellier&Belloit ammo groups exceedingly well in mine, and it is proofed for the 15 gramm bullet. I am less familiar with the rimless ammunition availability. The rimmed version is a cinch to find--picked up two boxes from Graffs a month ago for $19.95 a box of 20 plus free shipping! Don't know what the price will be on the rimless. Good luck. Sounds like an attractive rifle...maybe some additional photos? Steve