I am thinking the 22 ARC would be a good choice if I wanted to shoot the TMK and heavier -X and -M bullets. It seems you need a longer magazine or a faster twist than many 223 rifles have and Factory ammo using good bullets is very available. I thought about getting a 1-7 twist barrel for my Model Seven, lengthening the magazine and using it but then took a look at what was available for the 22 ARC, causing mixed thinking on the best route. Easy button is a bolt and barrel for an AR.