I was browsing MRC's new website and noticed they're chambering the 6XC and 22-250 in the XWR-SS line.
It will be interesting to see how they're twisted. I sent them an email asking specifics. Let's hope they twisted them fast...
I sent them an email a few weeks ago asking for some twist rates.
Here is the info provided:
308 1-10 Twist will stabilize between 110 grain to 220 Grain (probably the widest range of any caliber)
260 � 1-8.5 Twist will stabilize 130-160 Grain or the 1-9 Twist will stabilize 100-140 Grain
243 � 1-9 Twist which will stabilize 60 gr to 110 grain
270 � 1-10 Twist which will stabilize 90-150 Grain.