Sorry for the hijack...
The gain (if there is one) isn't significant enough to warrant an AR-15 type rifle in 545 in my opinion. Seems more of just a toy for someone who wants to be different.
AR mags are smaller, and lighter. It would require a lot of changes to the whole system to guarantee reliability I'd imagine. From the gas system, to carrier and buffer weights. Bah....it if ain't broke...
The only thing 545 has going for it, is less recoil than the 556 (which is pretty lame, since neither has ANY recoil...hell, I don't even like to use the word "recoil" and 556 in the same sentence)
And...
It is a long projectile that is very bottom heavy because of the cavity at the front. Pretty much the same thing that 68+ grain 556 ammo is accomplishing now. OTM is the same concept. Long projectile that is rear heavy = MUCH increased yaw. Yaw is good. While yaw doesn't guarantee fragmentation, it in itself is quite destructive. Earlier the yaw, the more destructive fragmentation can be.
Still, the nod goes to 556 since you get the same effect, but with a much bigger heavier bullet.
I would really, really hate to base my collection on a caliber whose primary source of ammunition is Wolf. Wolf isn't that great, and moreover....all it takes is 1 executive order to block the import of Wolf forever. Imagine the price for that stuff made domestically! ouch.