Drop-In Builds

What has to match your AR-15 barrel?

The barrel sets most of an AR-15 upper: its gas journal decides the gas block, its gas port position decides the gas tube, its caliber decides the bolt, and its threads decide the muzzle device.

The Short Answer

  • The gas block must match the barrel's gas journal diameter exactly, such as .625" or .750".
  • The gas tube must match the gas system length: pistol, carbine, midlength or rifle.
  • A 5.56 bolt runs 5.56 NATO, .223 Wylde and .300 Blackout barrels.
  • The muzzle device must match the barrel threads, and its bore has to be big enough for the bullet. A 5.56 device on a .30 caliber barrel can thread on and be struck by the bullet.
  • A free-float handguard needs a low-profile gas block. Drop-in handguards need an A2 front sight base.
Check Your Own AR-15 Build

Barrel and Gas Block

Every barrel we list, checked against every gas block.

Palmetto State Armory 16" 5.56 NATO Carbine, Nitride

  • Fits Aero Precision Low Profile Gas Block .750 · Superlative Arms Adjustable Bleed-Off Gas Block .750 · Palmetto State Armory A2 Front Sight Base .750, F-Marked · SLR Rifleworks Sentry 7 Adjustable Gas Block .750
  • Won't fit Aero Precision Low Profile Gas Block .625 · Superlative Arms Adjustable Bleed-Off Gas Block .625 The barrel has a .750" gas journal but the gas block is .625".

Ballistic Advantage 16" 5.56 Midlength Modern Series

  • Fits Aero Precision Low Profile Gas Block .750 · Superlative Arms Adjustable Bleed-Off Gas Block .750 · Palmetto State Armory A2 Front Sight Base .750, F-Marked · SLR Rifleworks Sentry 7 Adjustable Gas Block .750
  • Won't fit Aero Precision Low Profile Gas Block .625 · Superlative Arms Adjustable Bleed-Off Gas Block .625 The barrel has a .750" gas journal but the gas block is .625".

Faxon 16" Gunner Pencil, 5.56

  • Fits Aero Precision Low Profile Gas Block .625 · Superlative Arms Adjustable Bleed-Off Gas Block .625
  • Won't fit Aero Precision Low Profile Gas Block .750 · Superlative Arms Adjustable Bleed-Off Gas Block .750 · Palmetto State Armory A2 Front Sight Base .750, F-Marked · SLR Rifleworks Sentry 7 Adjustable Gas Block .750 The barrel has a .625" gas journal but the gas block is .750".

Bravo Company 16" Mid-16 Standard, 5.56

  • Fits Aero Precision Low Profile Gas Block .750 · Superlative Arms Adjustable Bleed-Off Gas Block .750 · Palmetto State Armory A2 Front Sight Base .750, F-Marked · SLR Rifleworks Sentry 7 Adjustable Gas Block .750
  • Won't fit Aero Precision Low Profile Gas Block .625 · Superlative Arms Adjustable Bleed-Off Gas Block .625 The barrel has a .750" gas journal but the gas block is .625".

Criterion 18" Hybrid SPR, .223 Wylde

  • Fits Aero Precision Low Profile Gas Block .750 · Superlative Arms Adjustable Bleed-Off Gas Block .750 · Palmetto State Armory A2 Front Sight Base .750, F-Marked · SLR Rifleworks Sentry 7 Adjustable Gas Block .750
  • Won't fit Aero Precision Low Profile Gas Block .625 · Superlative Arms Adjustable Bleed-Off Gas Block .625 The barrel has a .750" gas journal but the gas block is .625".

Ballistic Advantage 10.3" 5.56 Carbine Hanson

  • Fits Aero Precision Low Profile Gas Block .750 · Superlative Arms Adjustable Bleed-Off Gas Block .750 · Palmetto State Armory A2 Front Sight Base .750, F-Marked · SLR Rifleworks Sentry 7 Adjustable Gas Block .750
  • Won't fit Aero Precision Low Profile Gas Block .625 · Superlative Arms Adjustable Bleed-Off Gas Block .625 The barrel has a .750" gas journal but the gas block is .625".

Ballistic Advantage 16" .300 BLK Pistol-Length

  • Fits Aero Precision Low Profile Gas Block .750 · Superlative Arms Adjustable Bleed-Off Gas Block .750 · Palmetto State Armory A2 Front Sight Base .750, F-Marked · SLR Rifleworks Sentry 7 Adjustable Gas Block .750
  • Won't fit Aero Precision Low Profile Gas Block .625 · Superlative Arms Adjustable Bleed-Off Gas Block .625 The barrel has a .750" gas journal but the gas block is .625".

Aero Precision 16" 5.56 CMV Barrel, Mid-Length

  • Fits Aero Precision Low Profile Gas Block .750 · Superlative Arms Adjustable Bleed-Off Gas Block .750 · Palmetto State Armory A2 Front Sight Base .750, F-Marked · SLR Rifleworks Sentry 7 Adjustable Gas Block .750
  • Won't fit Aero Precision Low Profile Gas Block .625 · Superlative Arms Adjustable Bleed-Off Gas Block .625 The barrel has a .750" gas journal but the gas block is .625".

Ballistic Advantage 20" 5.56 Government Rifle-Length, Modern Series

  • Fits Aero Precision Low Profile Gas Block .750 · Superlative Arms Adjustable Bleed-Off Gas Block .750 · Palmetto State Armory A2 Front Sight Base .750, F-Marked · SLR Rifleworks Sentry 7 Adjustable Gas Block .750
  • Won't fit Aero Precision Low Profile Gas Block .625 · Superlative Arms Adjustable Bleed-Off Gas Block .625 The barrel has a .750" gas journal but the gas block is .625".

Ballistic Advantage 18" .223 Wylde SPR Fluted, Premium Series

  • Fits Aero Precision Low Profile Gas Block .750 · Superlative Arms Adjustable Bleed-Off Gas Block .750 · Palmetto State Armory A2 Front Sight Base .750, F-Marked · SLR Rifleworks Sentry 7 Adjustable Gas Block .750
  • Won't fit Aero Precision Low Profile Gas Block .625 · Superlative Arms Adjustable Bleed-Off Gas Block .625 The barrel has a .750" gas journal but the gas block is .625".

Ballistic Advantage 11.5" 5.56 Government Carbine, Modern Series

  • Fits Aero Precision Low Profile Gas Block .750 · Superlative Arms Adjustable Bleed-Off Gas Block .750 · Palmetto State Armory A2 Front Sight Base .750, F-Marked · SLR Rifleworks Sentry 7 Adjustable Gas Block .750
  • Won't fit Aero Precision Low Profile Gas Block .625 · Superlative Arms Adjustable Bleed-Off Gas Block .625 The barrel has a .750" gas journal but the gas block is .625".

Ballistic Advantage 7.5" 5.56 Pistol-Length, Modern Series

  • Fits Aero Precision Low Profile Gas Block .750 · Superlative Arms Adjustable Bleed-Off Gas Block .750 · Palmetto State Armory A2 Front Sight Base .750, F-Marked · SLR Rifleworks Sentry 7 Adjustable Gas Block .750
  • Won't fit Aero Precision Low Profile Gas Block .625 · Superlative Arms Adjustable Bleed-Off Gas Block .625 The barrel has a .750" gas journal but the gas block is .625".

Ballistic Advantage 9" .300 BLK Pistol-Length, Modern Series

  • Fits Aero Precision Low Profile Gas Block .750 · Superlative Arms Adjustable Bleed-Off Gas Block .750 · Palmetto State Armory A2 Front Sight Base .750, F-Marked · SLR Rifleworks Sentry 7 Adjustable Gas Block .750
  • Won't fit Aero Precision Low Profile Gas Block .625 · Superlative Arms Adjustable Bleed-Off Gas Block .625 The barrel has a .750" gas journal but the gas block is .625".

Ballistic Advantage 18" 6.5 Grendel SPR, Premium Series

  • Fits Aero Precision Low Profile Gas Block .750 · Superlative Arms Adjustable Bleed-Off Gas Block .750 · Palmetto State Armory A2 Front Sight Base .750, F-Marked · SLR Rifleworks Sentry 7 Adjustable Gas Block .750
  • Won't fit Aero Precision Low Profile Gas Block .625 · Superlative Arms Adjustable Bleed-Off Gas Block .625 The barrel has a .750" gas journal but the gas block is .625".

Faxon 20" 6.5 Grendel Match Series Heavy Fluted

  • Fits Aero Precision Low Profile Gas Block .750 · Superlative Arms Adjustable Bleed-Off Gas Block .750 · Palmetto State Armory A2 Front Sight Base .750, F-Marked · SLR Rifleworks Sentry 7 Adjustable Gas Block .750
  • Won't fit Aero Precision Low Profile Gas Block .625 · Superlative Arms Adjustable Bleed-Off Gas Block .625 The barrel has a .750" gas journal but the gas block is .625".

Ballistic Advantage 18" 6mm ARC SPR, Premium Series

  • Fits Aero Precision Low Profile Gas Block .750 · Superlative Arms Adjustable Bleed-Off Gas Block .750 · Palmetto State Armory A2 Front Sight Base .750, F-Marked · SLR Rifleworks Sentry 7 Adjustable Gas Block .750
  • Won't fit Aero Precision Low Profile Gas Block .625 · Superlative Arms Adjustable Bleed-Off Gas Block .625 The barrel has a .750" gas journal but the gas block is .625".

Barrel and Gas Tube

Gas tube length follows the barrel's gas system.

Palmetto State Armory 16" 5.56 NATO Carbine, Nitride

  • Fits Aero Precision Carbine-Length Gas Tube
  • Won't fit Aero Precision Pistol-Length Gas Tube The barrel is carbine-length gas but the gas tube is pistol-length. They must match.
  • Won't fit Aero Precision Midlength Gas Tube The barrel is carbine-length gas but the gas tube is midlength-length. They must match.
  • Won't fit Aero Precision Rifle-Length Gas Tube The barrel is carbine-length gas but the gas tube is rifle-length. They must match.

Ballistic Advantage 16" 5.56 Midlength Modern Series

  • Fits Aero Precision Midlength Gas Tube
  • Won't fit Aero Precision Pistol-Length Gas Tube The barrel is midlength-length gas but the gas tube is pistol-length. They must match.
  • Won't fit Aero Precision Carbine-Length Gas Tube The barrel is midlength-length gas but the gas tube is carbine-length. They must match.
  • Won't fit Aero Precision Rifle-Length Gas Tube The barrel is midlength-length gas but the gas tube is rifle-length. They must match.

Faxon 16" Gunner Pencil, 5.56

  • Fits Aero Precision Midlength Gas Tube
  • Won't fit Aero Precision Pistol-Length Gas Tube The barrel is midlength-length gas but the gas tube is pistol-length. They must match.
  • Won't fit Aero Precision Carbine-Length Gas Tube The barrel is midlength-length gas but the gas tube is carbine-length. They must match.
  • Won't fit Aero Precision Rifle-Length Gas Tube The barrel is midlength-length gas but the gas tube is rifle-length. They must match.

Bravo Company 16" Mid-16 Standard, 5.56

  • Fits Aero Precision Midlength Gas Tube
  • Won't fit Aero Precision Pistol-Length Gas Tube The barrel is midlength-length gas but the gas tube is pistol-length. They must match.
  • Won't fit Aero Precision Carbine-Length Gas Tube The barrel is midlength-length gas but the gas tube is carbine-length. They must match.
  • Won't fit Aero Precision Rifle-Length Gas Tube The barrel is midlength-length gas but the gas tube is rifle-length. They must match.

Criterion 18" Hybrid SPR, .223 Wylde

  • Fits Aero Precision Rifle-Length Gas Tube
  • Won't fit Aero Precision Pistol-Length Gas Tube The barrel is rifle-length gas but the gas tube is pistol-length. They must match.
  • Won't fit Aero Precision Carbine-Length Gas Tube The barrel is rifle-length gas but the gas tube is carbine-length. They must match.
  • Won't fit Aero Precision Midlength Gas Tube The barrel is rifle-length gas but the gas tube is midlength-length. They must match.

Ballistic Advantage 10.3" 5.56 Carbine Hanson

  • Fits Aero Precision Carbine-Length Gas Tube
  • Won't fit Aero Precision Pistol-Length Gas Tube The barrel is carbine-length gas but the gas tube is pistol-length. They must match.
  • Won't fit Aero Precision Midlength Gas Tube The barrel is carbine-length gas but the gas tube is midlength-length. They must match.
  • Won't fit Aero Precision Rifle-Length Gas Tube The barrel is carbine-length gas but the gas tube is rifle-length. They must match.

Ballistic Advantage 16" .300 BLK Pistol-Length

  • Fits Aero Precision Pistol-Length Gas Tube
  • Won't fit Aero Precision Carbine-Length Gas Tube The barrel is pistol-length gas but the gas tube is carbine-length. They must match.
  • Won't fit Aero Precision Midlength Gas Tube The barrel is pistol-length gas but the gas tube is midlength-length. They must match.
  • Won't fit Aero Precision Rifle-Length Gas Tube The barrel is pistol-length gas but the gas tube is rifle-length. They must match.

Aero Precision 16" 5.56 CMV Barrel, Mid-Length

  • Fits Aero Precision Midlength Gas Tube
  • Won't fit Aero Precision Pistol-Length Gas Tube The barrel is midlength-length gas but the gas tube is pistol-length. They must match.
  • Won't fit Aero Precision Carbine-Length Gas Tube The barrel is midlength-length gas but the gas tube is carbine-length. They must match.
  • Won't fit Aero Precision Rifle-Length Gas Tube The barrel is midlength-length gas but the gas tube is rifle-length. They must match.

Ballistic Advantage 20" 5.56 Government Rifle-Length, Modern Series

  • Fits Aero Precision Rifle-Length Gas Tube
  • Won't fit Aero Precision Pistol-Length Gas Tube The barrel is rifle-length gas but the gas tube is pistol-length. They must match.
  • Won't fit Aero Precision Carbine-Length Gas Tube The barrel is rifle-length gas but the gas tube is carbine-length. They must match.
  • Won't fit Aero Precision Midlength Gas Tube The barrel is rifle-length gas but the gas tube is midlength-length. They must match.

Ballistic Advantage 18" .223 Wylde SPR Fluted, Premium Series

  • Fits Aero Precision Rifle-Length Gas Tube
  • Won't fit Aero Precision Pistol-Length Gas Tube The barrel is rifle-length gas but the gas tube is pistol-length. They must match.
  • Won't fit Aero Precision Carbine-Length Gas Tube The barrel is rifle-length gas but the gas tube is carbine-length. They must match.
  • Won't fit Aero Precision Midlength Gas Tube The barrel is rifle-length gas but the gas tube is midlength-length. They must match.

Ballistic Advantage 11.5" 5.56 Government Carbine, Modern Series

  • Fits Aero Precision Carbine-Length Gas Tube
  • Won't fit Aero Precision Pistol-Length Gas Tube The barrel is carbine-length gas but the gas tube is pistol-length. They must match.
  • Won't fit Aero Precision Midlength Gas Tube The barrel is carbine-length gas but the gas tube is midlength-length. They must match.
  • Won't fit Aero Precision Rifle-Length Gas Tube The barrel is carbine-length gas but the gas tube is rifle-length. They must match.

Ballistic Advantage 7.5" 5.56 Pistol-Length, Modern Series

  • Fits Aero Precision Pistol-Length Gas Tube
  • Won't fit Aero Precision Carbine-Length Gas Tube The barrel is pistol-length gas but the gas tube is carbine-length. They must match.
  • Won't fit Aero Precision Midlength Gas Tube The barrel is pistol-length gas but the gas tube is midlength-length. They must match.
  • Won't fit Aero Precision Rifle-Length Gas Tube The barrel is pistol-length gas but the gas tube is rifle-length. They must match.

Ballistic Advantage 9" .300 BLK Pistol-Length, Modern Series

  • Fits Aero Precision Pistol-Length Gas Tube
  • Won't fit Aero Precision Carbine-Length Gas Tube The barrel is pistol-length gas but the gas tube is carbine-length. They must match.
  • Won't fit Aero Precision Midlength Gas Tube The barrel is pistol-length gas but the gas tube is midlength-length. They must match.
  • Won't fit Aero Precision Rifle-Length Gas Tube The barrel is pistol-length gas but the gas tube is rifle-length. They must match.

Ballistic Advantage 18" 6.5 Grendel SPR, Premium Series

  • Fits Aero Precision Rifle-Length Gas Tube
  • Won't fit Aero Precision Pistol-Length Gas Tube The barrel is rifle-length gas but the gas tube is pistol-length. They must match.
  • Won't fit Aero Precision Carbine-Length Gas Tube The barrel is rifle-length gas but the gas tube is carbine-length. They must match.
  • Won't fit Aero Precision Midlength Gas Tube The barrel is rifle-length gas but the gas tube is midlength-length. They must match.

Faxon 20" 6.5 Grendel Match Series Heavy Fluted

  • Fits Aero Precision Rifle-Length Gas Tube
  • Won't fit Aero Precision Pistol-Length Gas Tube The barrel is rifle-length gas but the gas tube is pistol-length. They must match.
  • Won't fit Aero Precision Carbine-Length Gas Tube The barrel is rifle-length gas but the gas tube is carbine-length. They must match.
  • Won't fit Aero Precision Midlength Gas Tube The barrel is rifle-length gas but the gas tube is midlength-length. They must match.

Ballistic Advantage 18" 6mm ARC SPR, Premium Series

  • Fits Aero Precision Rifle-Length Gas Tube
  • Won't fit Aero Precision Pistol-Length Gas Tube The barrel is rifle-length gas but the gas tube is pistol-length. They must match.
  • Won't fit Aero Precision Carbine-Length Gas Tube The barrel is rifle-length gas but the gas tube is carbine-length. They must match.
  • Won't fit Aero Precision Midlength Gas Tube The barrel is rifle-length gas but the gas tube is midlength-length. They must match.

Barrel and Bolt Carrier Group

The bolt face has to match the cartridge.

Palmetto State Armory 16" 5.56 NATO Carbine, Nitride

  • Fits Palmetto State Armory M16 Nitride BCG · Toolcraft M16 Nitride BCG · Bravo Company BCG M16 Auto Rated · Aero Precision 5.56 Bolt Carrier Group, Nitride
  • Won't fit Faxon 6.5 Grendel / 6mm ARC BCG A 5.56 barrel needs a 5.56 bolt; this BCG has a 6.5G bolt face.

Ballistic Advantage 16" 5.56 Midlength Modern Series

  • Fits Palmetto State Armory M16 Nitride BCG · Toolcraft M16 Nitride BCG · Bravo Company BCG M16 Auto Rated · Aero Precision 5.56 Bolt Carrier Group, Nitride
  • Won't fit Faxon 6.5 Grendel / 6mm ARC BCG A 5.56 barrel needs a 5.56 bolt; this BCG has a 6.5G bolt face.

Faxon 16" Gunner Pencil, 5.56

  • Fits Palmetto State Armory M16 Nitride BCG · Toolcraft M16 Nitride BCG · Bravo Company BCG M16 Auto Rated · Aero Precision 5.56 Bolt Carrier Group, Nitride
  • Won't fit Faxon 6.5 Grendel / 6mm ARC BCG A 5.56 barrel needs a 5.56 bolt; this BCG has a 6.5G bolt face.

Bravo Company 16" Mid-16 Standard, 5.56

  • Fits Palmetto State Armory M16 Nitride BCG · Toolcraft M16 Nitride BCG · Bravo Company BCG M16 Auto Rated · Aero Precision 5.56 Bolt Carrier Group, Nitride
  • Won't fit Faxon 6.5 Grendel / 6mm ARC BCG A 5.56 barrel needs a 5.56 bolt; this BCG has a 6.5G bolt face.

Criterion 18" Hybrid SPR, .223 Wylde

  • Fits Palmetto State Armory M16 Nitride BCG · Toolcraft M16 Nitride BCG · Bravo Company BCG M16 Auto Rated · Aero Precision 5.56 Bolt Carrier Group, Nitride
  • Won't fit Faxon 6.5 Grendel / 6mm ARC BCG A .223 Wylde barrel needs a 5.56 bolt; this BCG has a 6.5G bolt face.

Ballistic Advantage 10.3" 5.56 Carbine Hanson

  • Fits Palmetto State Armory M16 Nitride BCG · Toolcraft M16 Nitride BCG · Bravo Company BCG M16 Auto Rated · Aero Precision 5.56 Bolt Carrier Group, Nitride
  • Won't fit Faxon 6.5 Grendel / 6mm ARC BCG A 5.56 barrel needs a 5.56 bolt; this BCG has a 6.5G bolt face.

Ballistic Advantage 16" .300 BLK Pistol-Length

  • Fits Palmetto State Armory M16 Nitride BCG · Toolcraft M16 Nitride BCG · Bravo Company BCG M16 Auto Rated · Aero Precision 5.56 Bolt Carrier Group, Nitride
  • Won't fit Faxon 6.5 Grendel / 6mm ARC BCG A .300 BLK barrel needs a 5.56 bolt; this BCG has a 6.5G bolt face.

Aero Precision 16" 5.56 CMV Barrel, Mid-Length

  • Fits Palmetto State Armory M16 Nitride BCG · Toolcraft M16 Nitride BCG · Bravo Company BCG M16 Auto Rated · Aero Precision 5.56 Bolt Carrier Group, Nitride
  • Won't fit Faxon 6.5 Grendel / 6mm ARC BCG A 5.56 barrel needs a 5.56 bolt; this BCG has a 6.5G bolt face.

Ballistic Advantage 20" 5.56 Government Rifle-Length, Modern Series

  • Fits Palmetto State Armory M16 Nitride BCG · Toolcraft M16 Nitride BCG · Bravo Company BCG M16 Auto Rated · Aero Precision 5.56 Bolt Carrier Group, Nitride
  • Won't fit Faxon 6.5 Grendel / 6mm ARC BCG A 5.56 barrel needs a 5.56 bolt; this BCG has a 6.5G bolt face.

Ballistic Advantage 18" .223 Wylde SPR Fluted, Premium Series

  • Fits Palmetto State Armory M16 Nitride BCG · Toolcraft M16 Nitride BCG · Bravo Company BCG M16 Auto Rated · Aero Precision 5.56 Bolt Carrier Group, Nitride
  • Won't fit Faxon 6.5 Grendel / 6mm ARC BCG A .223 Wylde barrel needs a 5.56 bolt; this BCG has a 6.5G bolt face.

Ballistic Advantage 11.5" 5.56 Government Carbine, Modern Series

  • Fits Palmetto State Armory M16 Nitride BCG · Toolcraft M16 Nitride BCG · Bravo Company BCG M16 Auto Rated · Aero Precision 5.56 Bolt Carrier Group, Nitride
  • Won't fit Faxon 6.5 Grendel / 6mm ARC BCG A 5.56 barrel needs a 5.56 bolt; this BCG has a 6.5G bolt face.

Ballistic Advantage 7.5" 5.56 Pistol-Length, Modern Series

  • Fits Palmetto State Armory M16 Nitride BCG · Toolcraft M16 Nitride BCG · Bravo Company BCG M16 Auto Rated · Aero Precision 5.56 Bolt Carrier Group, Nitride
  • Won't fit Faxon 6.5 Grendel / 6mm ARC BCG A 5.56 barrel needs a 5.56 bolt; this BCG has a 6.5G bolt face.

Ballistic Advantage 9" .300 BLK Pistol-Length, Modern Series

  • Fits Palmetto State Armory M16 Nitride BCG · Toolcraft M16 Nitride BCG · Bravo Company BCG M16 Auto Rated · Aero Precision 5.56 Bolt Carrier Group, Nitride
  • Won't fit Faxon 6.5 Grendel / 6mm ARC BCG A .300 BLK barrel needs a 5.56 bolt; this BCG has a 6.5G bolt face.

Ballistic Advantage 18" 6.5 Grendel SPR, Premium Series

  • Fits Faxon 6.5 Grendel / 6mm ARC BCG
  • Won't fit Palmetto State Armory M16 Nitride BCG · Toolcraft M16 Nitride BCG · Bravo Company BCG M16 Auto Rated · Aero Precision 5.56 Bolt Carrier Group, Nitride A 6.5 Grendel barrel needs a 6.5G bolt; this BCG has a 5.56 bolt face.

Faxon 20" 6.5 Grendel Match Series Heavy Fluted

  • Fits Faxon 6.5 Grendel / 6mm ARC BCG
  • Won't fit Palmetto State Armory M16 Nitride BCG · Toolcraft M16 Nitride BCG · Bravo Company BCG M16 Auto Rated · Aero Precision 5.56 Bolt Carrier Group, Nitride A 6.5 Grendel barrel needs a 6.5G bolt; this BCG has a 5.56 bolt face.

Ballistic Advantage 18" 6mm ARC SPR, Premium Series

  • Fits Faxon 6.5 Grendel / 6mm ARC BCG
  • Won't fit Palmetto State Armory M16 Nitride BCG · Toolcraft M16 Nitride BCG · Bravo Company BCG M16 Auto Rated · Aero Precision 5.56 Bolt Carrier Group, Nitride A 6mm ARC barrel needs a 6.5G bolt; this BCG has a 5.56 bolt face.

Barrel and Muzzle Device

Thread pitch and bore size.

Palmetto State Armory 16" 5.56 NATO Carbine, Nitride

  • Fits Generic A2 Birdcage Flash Hider · Lantac Dragon Muzzle Brake 5.56 · SureFire WarComp 5.56 · VG6 Precision Gamma 556 Muzzle Brake · SureFire SOCOM 3-Prong Flash Hider 5.56
  • Won't fit Precision Armament M4-72 Severe Duty Brake (5/8x24) · Generic A2 Flash Hider .30 Cal (5/8x24) · SureFire SOCOM 3-Prong Flash Hider 7.62 (5/8x24) The barrel is threaded 1/2x28 but the muzzle device is 5/8x24. They won't screw together.

Ballistic Advantage 16" 5.56 Midlength Modern Series

  • Fits Generic A2 Birdcage Flash Hider · Lantac Dragon Muzzle Brake 5.56 · SureFire WarComp 5.56 · VG6 Precision Gamma 556 Muzzle Brake · SureFire SOCOM 3-Prong Flash Hider 5.56
  • Won't fit Precision Armament M4-72 Severe Duty Brake (5/8x24) · Generic A2 Flash Hider .30 Cal (5/8x24) · SureFire SOCOM 3-Prong Flash Hider 7.62 (5/8x24) The barrel is threaded 1/2x28 but the muzzle device is 5/8x24. They won't screw together.

Faxon 16" Gunner Pencil, 5.56

  • Fits Generic A2 Birdcage Flash Hider · Lantac Dragon Muzzle Brake 5.56 · SureFire WarComp 5.56 · VG6 Precision Gamma 556 Muzzle Brake · SureFire SOCOM 3-Prong Flash Hider 5.56
  • Won't fit Precision Armament M4-72 Severe Duty Brake (5/8x24) · Generic A2 Flash Hider .30 Cal (5/8x24) · SureFire SOCOM 3-Prong Flash Hider 7.62 (5/8x24) The barrel is threaded 1/2x28 but the muzzle device is 5/8x24. They won't screw together.

Bravo Company 16" Mid-16 Standard, 5.56

  • Fits Generic A2 Birdcage Flash Hider · Lantac Dragon Muzzle Brake 5.56 · SureFire WarComp 5.56 · VG6 Precision Gamma 556 Muzzle Brake · SureFire SOCOM 3-Prong Flash Hider 5.56
  • Won't fit Precision Armament M4-72 Severe Duty Brake (5/8x24) · Generic A2 Flash Hider .30 Cal (5/8x24) · SureFire SOCOM 3-Prong Flash Hider 7.62 (5/8x24) The barrel is threaded 1/2x28 but the muzzle device is 5/8x24. They won't screw together.

Criterion 18" Hybrid SPR, .223 Wylde

  • Fits Generic A2 Birdcage Flash Hider · Lantac Dragon Muzzle Brake 5.56 · SureFire WarComp 5.56 · VG6 Precision Gamma 556 Muzzle Brake · SureFire SOCOM 3-Prong Flash Hider 5.56
  • Won't fit Precision Armament M4-72 Severe Duty Brake (5/8x24) · Generic A2 Flash Hider .30 Cal (5/8x24) · SureFire SOCOM 3-Prong Flash Hider 7.62 (5/8x24) The barrel is threaded 1/2x28 but the muzzle device is 5/8x24. They won't screw together.

Ballistic Advantage 10.3" 5.56 Carbine Hanson

  • Fits Generic A2 Birdcage Flash Hider · Lantac Dragon Muzzle Brake 5.56 · SureFire WarComp 5.56 · VG6 Precision Gamma 556 Muzzle Brake · SureFire SOCOM 3-Prong Flash Hider 5.56
  • Won't fit Precision Armament M4-72 Severe Duty Brake (5/8x24) · Generic A2 Flash Hider .30 Cal (5/8x24) · SureFire SOCOM 3-Prong Flash Hider 7.62 (5/8x24) The barrel is threaded 1/2x28 but the muzzle device is 5/8x24. They won't screw together.

Ballistic Advantage 16" .300 BLK Pistol-Length

  • Fits Precision Armament M4-72 Severe Duty Brake (5/8x24) · Generic A2 Flash Hider .30 Cal (5/8x24) · SureFire SOCOM 3-Prong Flash Hider 7.62 (5/8x24)
  • Won't fit Generic A2 Birdcage Flash Hider · Lantac Dragon Muzzle Brake 5.56 · SureFire WarComp 5.56 · VG6 Precision Gamma 556 Muzzle Brake · SureFire SOCOM 3-Prong Flash Hider 5.56 The barrel is threaded 5/8x24 but the muzzle device is 1/2x28. They won't screw together.

Aero Precision 16" 5.56 CMV Barrel, Mid-Length

  • Fits Generic A2 Birdcage Flash Hider · Lantac Dragon Muzzle Brake 5.56 · SureFire WarComp 5.56 · VG6 Precision Gamma 556 Muzzle Brake · SureFire SOCOM 3-Prong Flash Hider 5.56
  • Won't fit Precision Armament M4-72 Severe Duty Brake (5/8x24) · Generic A2 Flash Hider .30 Cal (5/8x24) · SureFire SOCOM 3-Prong Flash Hider 7.62 (5/8x24) The barrel is threaded 1/2x28 but the muzzle device is 5/8x24. They won't screw together.

Ballistic Advantage 20" 5.56 Government Rifle-Length, Modern Series

  • Fits Generic A2 Birdcage Flash Hider · Lantac Dragon Muzzle Brake 5.56 · SureFire WarComp 5.56 · VG6 Precision Gamma 556 Muzzle Brake · SureFire SOCOM 3-Prong Flash Hider 5.56
  • Won't fit Precision Armament M4-72 Severe Duty Brake (5/8x24) · Generic A2 Flash Hider .30 Cal (5/8x24) · SureFire SOCOM 3-Prong Flash Hider 7.62 (5/8x24) The barrel is threaded 1/2x28 but the muzzle device is 5/8x24. They won't screw together.

Ballistic Advantage 18" .223 Wylde SPR Fluted, Premium Series

  • Fits Generic A2 Birdcage Flash Hider · Lantac Dragon Muzzle Brake 5.56 · SureFire WarComp 5.56 · VG6 Precision Gamma 556 Muzzle Brake · SureFire SOCOM 3-Prong Flash Hider 5.56
  • Won't fit Precision Armament M4-72 Severe Duty Brake (5/8x24) · Generic A2 Flash Hider .30 Cal (5/8x24) · SureFire SOCOM 3-Prong Flash Hider 7.62 (5/8x24) The barrel is threaded 1/2x28 but the muzzle device is 5/8x24. They won't screw together.

Ballistic Advantage 11.5" 5.56 Government Carbine, Modern Series

  • Fits Generic A2 Birdcage Flash Hider · Lantac Dragon Muzzle Brake 5.56 · SureFire WarComp 5.56 · VG6 Precision Gamma 556 Muzzle Brake · SureFire SOCOM 3-Prong Flash Hider 5.56
  • Won't fit Precision Armament M4-72 Severe Duty Brake (5/8x24) · Generic A2 Flash Hider .30 Cal (5/8x24) · SureFire SOCOM 3-Prong Flash Hider 7.62 (5/8x24) The barrel is threaded 1/2x28 but the muzzle device is 5/8x24. They won't screw together.

Ballistic Advantage 7.5" 5.56 Pistol-Length, Modern Series

  • Fits Generic A2 Birdcage Flash Hider · Lantac Dragon Muzzle Brake 5.56 · SureFire WarComp 5.56 · VG6 Precision Gamma 556 Muzzle Brake · SureFire SOCOM 3-Prong Flash Hider 5.56
  • Won't fit Precision Armament M4-72 Severe Duty Brake (5/8x24) · Generic A2 Flash Hider .30 Cal (5/8x24) · SureFire SOCOM 3-Prong Flash Hider 7.62 (5/8x24) The barrel is threaded 1/2x28 but the muzzle device is 5/8x24. They won't screw together.

Ballistic Advantage 9" .300 BLK Pistol-Length, Modern Series

  • Fits Precision Armament M4-72 Severe Duty Brake (5/8x24) · Generic A2 Flash Hider .30 Cal (5/8x24) · SureFire SOCOM 3-Prong Flash Hider 7.62 (5/8x24)
  • Won't fit Generic A2 Birdcage Flash Hider · Lantac Dragon Muzzle Brake 5.56 · SureFire WarComp 5.56 · VG6 Precision Gamma 556 Muzzle Brake · SureFire SOCOM 3-Prong Flash Hider 5.56 The barrel is threaded 5/8x24 but the muzzle device is 1/2x28. They won't screw together.

Ballistic Advantage 18" 6.5 Grendel SPR, Premium Series

  • Fits Precision Armament M4-72 Severe Duty Brake (5/8x24) · Generic A2 Flash Hider .30 Cal (5/8x24) · SureFire SOCOM 3-Prong Flash Hider 7.62 (5/8x24)
  • Won't fit Generic A2 Birdcage Flash Hider · Lantac Dragon Muzzle Brake 5.56 · SureFire WarComp 5.56 · VG6 Precision Gamma 556 Muzzle Brake · SureFire SOCOM 3-Prong Flash Hider 5.56 The barrel is threaded 5/8x24 but the muzzle device is 1/2x28. They won't screw together.

Faxon 20" 6.5 Grendel Match Series Heavy Fluted

  • Fits Precision Armament M4-72 Severe Duty Brake (5/8x24) · Generic A2 Flash Hider .30 Cal (5/8x24) · SureFire SOCOM 3-Prong Flash Hider 7.62 (5/8x24)
  • Won't fit Generic A2 Birdcage Flash Hider · Lantac Dragon Muzzle Brake 5.56 · SureFire WarComp 5.56 · VG6 Precision Gamma 556 Muzzle Brake · SureFire SOCOM 3-Prong Flash Hider 5.56 The barrel is threaded 5/8x24 but the muzzle device is 1/2x28. They won't screw together.

Ballistic Advantage 18" 6mm ARC SPR, Premium Series

  • Fits Precision Armament M4-72 Severe Duty Brake (5/8x24) · Generic A2 Flash Hider .30 Cal (5/8x24) · SureFire SOCOM 3-Prong Flash Hider 7.62 (5/8x24)
  • Won't fit Generic A2 Birdcage Flash Hider · Lantac Dragon Muzzle Brake 5.56 · SureFire WarComp 5.56 · VG6 Precision Gamma 556 Muzzle Brake · SureFire SOCOM 3-Prong Flash Hider 5.56 The barrel is threaded 5/8x24 but the muzzle device is 1/2x28. They won't screw together.

Gas Block and Handguard

What fits under each handguard.

Aero Precision Low Profile Gas Block .750

  • Fits Palmetto State Armory 13.5" Lightweight M-LOK Rail · Midwest Industries Combat Rail 15" M-LOK · Bravo Company MCMR-13 M-LOK Rail · Midwest Industries Combat Rail 9.25" M-LOK · Aero Precision ATLAS S-ONE 9.2" M-LOK · Bravo Company MCMR-10 M-LOK Rail · Geissele MK16 Super Modular Rail 13.5" M-LOK · Aero Precision ATLAS S-ONE 15" M-LOK · Midwest Industries Combat Rail 7" M-LOK
  • Won't fit Magpul MOE Drop-In Handguard, Midlength · Magpul MOE M-LOK Drop-In Handguard, Carbine · Magpul MOE M-LOK Drop-In Handguard, Rifle Drop-in handguards are held by the front sight base cap. Pair it with an A2 front sight base.

Superlative Arms Adjustable Bleed-Off Gas Block .750

  • Fits Palmetto State Armory 13.5" Lightweight M-LOK Rail · Midwest Industries Combat Rail 15" M-LOK · Bravo Company MCMR-13 M-LOK Rail · Midwest Industries Combat Rail 9.25" M-LOK · Aero Precision ATLAS S-ONE 9.2" M-LOK · Bravo Company MCMR-10 M-LOK Rail · Geissele MK16 Super Modular Rail 13.5" M-LOK · Aero Precision ATLAS S-ONE 15" M-LOK · Midwest Industries Combat Rail 7" M-LOK
  • Won't fit Magpul MOE Drop-In Handguard, Midlength · Magpul MOE M-LOK Drop-In Handguard, Carbine · Magpul MOE M-LOK Drop-In Handguard, Rifle Drop-in handguards are held by the front sight base cap. Pair it with an A2 front sight base.

Aero Precision Low Profile Gas Block .625

  • Fits Palmetto State Armory 13.5" Lightweight M-LOK Rail · Midwest Industries Combat Rail 15" M-LOK · Bravo Company MCMR-13 M-LOK Rail · Midwest Industries Combat Rail 9.25" M-LOK · Aero Precision ATLAS S-ONE 9.2" M-LOK · Bravo Company MCMR-10 M-LOK Rail · Geissele MK16 Super Modular Rail 13.5" M-LOK · Aero Precision ATLAS S-ONE 15" M-LOK · Midwest Industries Combat Rail 7" M-LOK
  • Won't fit Magpul MOE Drop-In Handguard, Midlength · Magpul MOE M-LOK Drop-In Handguard, Carbine · Magpul MOE M-LOK Drop-In Handguard, Rifle Drop-in handguards are held by the front sight base cap. Pair it with an A2 front sight base.

Palmetto State Armory A2 Front Sight Base .750, F-Marked

  • Fits Magpul MOE Drop-In Handguard, Midlength · Magpul MOE M-LOK Drop-In Handguard, Carbine · Magpul MOE M-LOK Drop-In Handguard, Rifle
  • Won't fit Palmetto State Armory 13.5" Lightweight M-LOK Rail · Midwest Industries Combat Rail 15" M-LOK · Bravo Company MCMR-13 M-LOK Rail · Midwest Industries Combat Rail 9.25" M-LOK · Aero Precision ATLAS S-ONE 9.2" M-LOK · Bravo Company MCMR-10 M-LOK Rail · Geissele MK16 Super Modular Rail 13.5" M-LOK · Aero Precision ATLAS S-ONE 15" M-LOK · Midwest Industries Combat Rail 7" M-LOK An A2 front sight base will not fit under a free-float handguard. Use a low-profile gas block.

SLR Rifleworks Sentry 7 Adjustable Gas Block .750

  • Fits Palmetto State Armory 13.5" Lightweight M-LOK Rail · Midwest Industries Combat Rail 15" M-LOK · Bravo Company MCMR-13 M-LOK Rail · Midwest Industries Combat Rail 9.25" M-LOK · Aero Precision ATLAS S-ONE 9.2" M-LOK · Bravo Company MCMR-10 M-LOK Rail · Geissele MK16 Super Modular Rail 13.5" M-LOK · Aero Precision ATLAS S-ONE 15" M-LOK · Midwest Industries Combat Rail 7" M-LOK
  • Won't fit Magpul MOE Drop-In Handguard, Midlength · Magpul MOE M-LOK Drop-In Handguard, Carbine · Magpul MOE M-LOK Drop-In Handguard, Rifle Drop-in handguards are held by the front sight base cap. Pair it with an A2 front sight base.

Superlative Arms Adjustable Bleed-Off Gas Block .625

  • Fits Palmetto State Armory 13.5" Lightweight M-LOK Rail · Midwest Industries Combat Rail 15" M-LOK · Bravo Company MCMR-13 M-LOK Rail · Midwest Industries Combat Rail 9.25" M-LOK · Aero Precision ATLAS S-ONE 9.2" M-LOK · Bravo Company MCMR-10 M-LOK Rail · Geissele MK16 Super Modular Rail 13.5" M-LOK · Aero Precision ATLAS S-ONE 15" M-LOK · Midwest Industries Combat Rail 7" M-LOK
  • Won't fit Magpul MOE Drop-In Handguard, Midlength · Magpul MOE M-LOK Drop-In Handguard, Carbine · Magpul MOE M-LOK Drop-In Handguard, Rifle Drop-in handguards are held by the front sight base cap. Pair it with an A2 front sight base.

Parts Worth a Look

Our picks from the AR-15 catalog, with the lowest price we list (prices last checked Oct 5, 2026).

Barrel

Budget Pick

Palmetto State Armory 16" 5.56 NATO Carbine, Nitride

16" · 5.56 NATO · Carbine gas · .750 journal · 1:7 · 1/2x28 thread

Reliable carbine-gas barrel at the lowest price.

$109.99 at Palmetto State Armory (sample price)

Best Value

Ballistic Advantage 16" 5.56 Midlength Modern Series

16" · 5.56 NATO · Midlength gas · .750 journal · 1:7 · 1/2x28 thread

Midlength gas runs softer than carbine gas on a 16" barrel.

$159.99 at Primary Arms (sample price)

Premium Pick

Bravo Company 16" Mid-16 Standard, 5.56

16" · 5.56 NATO · Midlength gas · .750 journal · Chrome lined · 1/2x28 thread

Chrome-lined, HPT/MPI tested, duty-grade.

$254.95 at Brownells (sample price)

Gas Block

Best Value

Aero Precision Low Profile Gas Block .750

.750 · Low profile · Set screw

Simple, fits under any free-float rail.

$22.99 at Primary Arms (sample price)

Premium Pick

Superlative Arms Adjustable Bleed-Off Gas Block .750

.750 · Low profile · Adjustable

Tune recoil and suppressed gas without tools.

$84.99 at Brownells (sample price)

Start from a Complete Build

Every part already checked to fit. Open one in the builder and swap anything you like.

Budget AR-1514 parts, $545.82 at the lowest prices we listBest Value AR-1515 parts, $1,262.74 at the lowest prices we listPremium AR-1515 parts, $2,297.60 at the lowest prices we list

Sources

Updated Oct 6, 2026.

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