List of AR platform calibers

The AR platform has become widely popular for makers of military and sporting rifles. Although the designations "AR-10" and "AR-15" are trademarks of Colt's Manufacturing Company variants of both are made by many manufacturers.

AR-15 calibers

Original caliber: 5.56×45mm NATO

Rimfire calibers

• .17 HMR
• .17 Winchester Super Magnum
• .22 Long Rifle
• .22 Winchester Magnum Rimfire

Centerfire calibers inch measurement

• .17 Mach IV
• .17 Remington Fireball
• .17 Remington
• .17×223
• .17 Tactical
• .20 Tactical
• .20 Practical
• .204 Ruger
• .20 PPC
• .20×6.8 (BHW)
• .20 LBC (BHW)
• .222 Remington
• .223 Remington - .223 cartridges may function in a 5.56×45mm rifle, however 5.56×45mm cartridges can produce excessive pressure in a .223 rifle.
• .223 Remington Ackley Improved
• .22 PPC
• .22 LBC (BHW)
• .22×6.8 (BHW)
• .243 LBC (BHW)
• .223 Winchester Super Short Magnum
• .243 Winchester Super Short Magnum
• .25 Winchester Super Short Magnum
• .25-45 Sharps
• .25×6.8 (BHW)
• .264 LBC (BHW)
• .270 AR
• .277 Wolverine (6.8×39mm)
• .30 Carbine
• .30 Herrett (.308-6.8)
• American 30 (BHW)
• .30 Remington AR
• 300 AAC Blackout (7.62×35mm)
• .300 Whisper
• 30×6.8 (BHW)
• .338×39
• .35×44 (BHW)
• 338 spectre
• 357 Automag
• 375 Automag
• .375 Reaper
• 375 SOCOM
• .40 S&W
• 44 Remington Magnum
• 44 Automag
• 440 Corbon Mag
• .45 ACP
• .450 Bushmaster
• .458 SOCOM
• 475 Tremor
• .50 Beowulf
• .50 Action Express

Centerfire calibers metric measurement

• 5.45×39mm
• 5.56×42mm(5.56-6.8)
• 5.56×45mm NATO (can also safely fire .223 Remington)
• FN 5.7×28mm
• 6×45mm
• 6×6.8 (BHW)
• 6mm Hagar
• 6mm PPC
• 6mm AR, a necked-down 6.5 Grendel
• 6mm AR Turbo, 6mm Dasher, 6mm Fat Rat (6mm Grendel AI) and other variants of the above cartridge
• 6PDK, a necked-down 6.8mm Remington SPC
• 6mm BRX
• 6.5mm BRX
• 6.5/6.8 (BHW)
• 6.5mm Grendel
• 6.5mm Patriot Combat Cartridge
• 6.8×39mm (.277 Wolverine)
• 6.8mm Remington SPC
• 7mm Valkyrie
• 7.62×37mm Musang
• 7.62×39mm
• 7.62×40mm Wilson Tactical
• 9mm Parabellum
• 10mm Auto
• 10mm SOCOM

Calibers which will not feed but which are used in rifles where the receiver functions only as a trigger group

• .50 BMG
• .408 CheyTac
• .338 Lapua Magnum
• .300 Winchester Magnum

AR-10 calibers

Original caliber: 7.62×51mm NATO

Center fire calibers

• .243 Winchester
• .260 Remington
• 6.5mm Creedmoor
• 6mm Creedmoor
• 6×47mm Lapua
• 6.5×47mm Lapua
• 7mm-08 Remington
• .308 Winchester - considered interchangeable with 7.62×51mm NATO according to SAAMI.
• .338 Federal
• .358 Winchester
• .45 RAPTOR

References

BHW designated chamberings based on the 6.8 SPC and the 6.5 Grendel were developed by Black Hole Weaponry using their own reamer designs. As they are non-SAAMI cartridges some confusion may exist as each manufacturer makes changes in their own designs that while identically named they are actually different in specifications. GLS