I have a lead on a CZ 550 rechambered to 450 ackley. Can this chambering shoot 458 Win Mag safely. I have read differing opinions in other places, just want to know what the experts think.

I have a 450 Ackley built on a P14 enfield action. As belted cases do headspace on the belt, yes you can fire 458 win Mag in your ackley (kind of like shooting 22 shorts in your 22 LR). You can also shoot 458 Lott ammo in it. It's quite a versatile caliber, really. - dan

Jump on it- The 450 Ackley is a better round than the Lott and yes you can shoot 458win mags out of it in an emergency.-Rob

I concur on the 458 ammo. I've got a friend who has a 450 Ack in a Mark X. The only problem is that it weighs 8 lbs...whew!