I built mine on a Savage 10, you can get much higher velocities because a bolt gun can handle pressures that would blow an AR to tiny pieces. this is from the 458 SOCOM forum a while back. Check out the Lehigh Defense 570 grain bullets !!
So that's my bullet of choice but I don't need it to cycle as I built a bolt gun. If you've never done a Savage build it's super easy. How easy ?? Think "I must be doing something wrong because it's too easy" easy, cuz that's how easy.
I started with a used model 11 in .243 Win from Gunbroker for $240(any of the short actions based on the .308 work,22-250,etc). A couple tools; action wrench, barrel nut wrench, go-gage.
The scope almost fell of and the trigger broke at almost 6lbs so I can tell this was no tack driver, might be why they sold it so cheap because Savages are accurate.
Loosen the barrel nut(basically a jam nut) then unscrew the barrel.
Put the nut and recoil lug on the new barrel, a 16" 1-10" twist threaded for brake $250 from Apache Gun Works.
Screw it in until you lightly contact the bolt face. Put the "Go" gage in, like chambering a bullet, and lightly try to close the bolt. You will unscrew the barrel until the bolt does close. Then remove the go gage and put in the no-go gage. The bolt should not close.
Bolt closed on go gage
Bolt not closed on no-go gage
That is it, setting the headspace is done !
Then tighten the barrel nut and recheck the headspace to ensure it didn't move.
Bullets fit nicely in the stock mag....compare the 570 Lehigh.
It is a beast !
Harrel's Precision 4 port tactical brake, ports are at 10 & 2 o'clock to tame muzzle jump.
It's a brass bullet which I have no experience with but have been reloading rifle, pistol, and shotgun rounds for many years. Lots of 300 Blackout subs too !!
Thanks