6XC - based on the 22-250 instead of the 243. It's slightly shorter than 243-based wildcats, and therefore able to take advantage of the longer 105gr+ bullets without concern for COAL in a BDL/ADL internal box. It's inherently accurate as well, and was developed by David Tubb primarily for XTC competitions. I've had a number of 6mm wildcats, and it remains in my stable while the others have been sent down the road for various reasons.
Gonna be a single shot and I don't want the 6XC- brass is very hard to find at most times.
