Just some useful information on what Calibers work with each platform.
Centerfire calibers inch measurement
.223 Remington - .223 cartridges may function in a 5.56×45mm rifle, however 5.56×45mm cartridges will produce excessive pressure in a .223 rifle.
.223 Remington Ackley Improved
.243 Winchester Super Short Magnum
.25 Winchester Super Short Magnum
.277 Wolverine (6.8×39mm)
.30 Herrett (.308-6.8)
.30 Remington AR
300 AAC Blackout (7.62×35mm)
.50 Action Express
Centerfire calibers metric measurement
6mm Fat Rat (6mm Grendel AI)
6mm AR Turbo
6.5mm Patriot Combat Cartridge
6.8×39mm (.277 Wolverine)
6.8mm Remington SPC
7.62×40mm Wilson Tactical
Calibers which will not feed but which are used in rifles where the receiver functions only as a trigger group
.338 Lapua Magnum
.300 Winchester Magnum
Center fire caliber
Original caliber: 7.62×51mm NATO
.308 Winchester - considered interchangeable with 7.62×51mm NATO according to SAAMI.