So Valkyrie is good for AR but not for bolt action because of brass availability. You don’t need brass for an AR?
Right now it is looking like you have to buy ammo, brass alone is not very available. Yes, it produces more speed with a heavy for caliber bullet, and fits in an AR platform. It out performs the .223/5.56mm in that aspect.
When a guy wants to produce high speed with a heavy for caliber .224 bullet, and is not restricted to the AR platform parameters, the .223, .223 A.I., the .22-250, .220 Swift, and .22-243 are all options, that have been doing it a long time, have plenty of brass available, and all but one on that list will out perform the Valkyrie.
I've recently been shooting the pee out of a .223 A.I. fire forming, with 80 gr ELD-M. And to say having one is pointless is just not so. It is a ton of fun to shoot! I am getting the same practice, with a bolt action that handles exactly like my 6.5 Creedmoor, but I am burning literally half the powder, and saving barrel life on the 6.5 Creedmoor. And it runs on widely available brass. Some guys go the Lake City route (very inexpensive and very plentiful) some go the Lapua route. I went with Lapua. I am told a ~3000 round barrel life, and I am asking 400 pieces to get there. They may make their way over to the next barrel, I don't know, only time will tell.