AR Platform Caliber Compatibility Guide: AR-15, AR-10, and AR-9

The AR platform is renowned for its versatility, accommodating a wide range of calibers. This guide provides a comprehensive overview of the calibers supported by the AR-15 (small frame), AR-10 (large frame), and AR-9 (pistol caliber carbine) platforms. Please make sure to select the correct AR Gold caliber variation to fit your rifle.

AR-15 Calibers (Small Frame):

• Common/Standard:
  • .223 Remington
  • 5.56x45mm NATO
• Popular Variations:
  • .22 Long Rifle (.22LR) (with dedicated upper/conversion)
  • .204 Ruger
  • .224 Valkyrie
  • 6mm ARC (Advanced Rifle Cartridge)
  • 6.5 Grendel
  • 6.8 SPC (Special Purpose Cartridge)
  • .300 AAC Blackout (.300 BLK)
  • .350 Legend
  • .450 Bushmaster
  • .458 SOCOM
  • .50 Beowulf
• Other:
  • .17 Remington
  • .25-45 Sharps
  • 7.62x39mm (with dedicated parts)
  • 9mm (with dedicated lower/upper)
  • .40 S&W (with dedicated lower/upper)
  • 10mm Auto (with dedicated lower/upper)

AR-10 Calibers (Large Frame):

• Common/Standard:
  • .308 Winchester (7.62x51mm NATO)
• Popular Variations:
  • 6.5 Creedmoor
  • .243 Winchester
  • .260 Remington
  • 7mm-08 Remington
  • .338 Federal
  • .450 Marlin
• Other:
  • .22-250 Remington
  • .30-06 Springfield (less common, requires specific parts)
  • .300 Winchester Magnum (less common, requires specific parts)

AR-9 Calibers (PCC - Pistol Caliber Carbine):

• Common/Standard:
  • 9x19mm Parabellum (9mm)
• Popular Variations:
  • .40 S&W
  • .45 ACP (Automatic Colt Pistol)
  • 10mm Auto
• Other:
  • .357 SIG

Important Considerations:

• Platform-Specific Compatibility: Compatibility within each platform depends on the specific barrel, bolt, magazine, and lower receiver used.
• Specialized Parts: Some calibers require specialized parts or conversions.
• Professional Guidance: Always consult with the firearm manufacturer or a qualified gunsmith to ensure proper compatibility and safe operation.
• AR-9 Variability: The AR-9 platform exhibits the most variability in compatibility due to the lack of industry-wide standardization.
• Caliber Conversions: Caliber conversions are common across all platforms, primarily through upper receiver changes.

Disclaimer:

This list is not exhaustive, and new cartridges and variations are continually being developed. Always verify compatibility with your specific firearm and components.

This separate article will allow people to easily find the information they are looking for without having to sort through a large compatibility article.