The entry level doesn't have a free floated barrel,nor is the barrel threaded for a muzzle break/flash arrester. The mid grade does.
I prefer the 458 SOCOM over the 50 Beowulf,but the 458 is really a handloaders caliber. Unless you know where you can find any ammo for these big bore AR's,now isn't the time to buy one unless you just want to look at it for a while. Ammo,and Reloading supplies are in very short supply.