I've no interest with a .473" or greater boltface on a '15. Go AR-10 of course and you've 2.800" or better COAL to work with. I'd much rather have a 243 or 243AI on a '10,than any 6mm shoe-horned into a '15. Fact is a "short" barreled SAAMI 243Win on a '10,is a rather wicked machine. I'm not hip on feeding self shuckers with brass that's $1 a pop,while polishing a turd to boot.

I'd hang pics,but someone would wanna pay me to place them in a magazine. Pun intended.

The 6BR/X as a LR belly gun in F-Class or similar,are typically laden with very long spouts,many of which are 28" if not 30". Pass the 22" 243/243AI and hold the fluff.