Brownells 75th Anniversary - A Shooting Heritage

Completely & Ready To Install - Converts a Standard AR to .30 Caliber

Consider Smith & Wesson’s M&P15 .300 Whisper Complete Upper Receiver Assembly if you’d like to turn an old AR-15 into a compact, versatile .30 caliber Modern Sporting Rifle capable of dropping deer-sized game. Or build a complete rifle from the ground up using the lower receiver, buffer tube, and stock of your choice.

The Smith & Wesson M&P15 .300 Whisper complete upper receiver comes fully assembled and fitted with popular features. Feed ramps in the A4-pattern flattop receiver and the gas system are optimized to run efficiently with a wide range of factory loaded subsonic and supersonic ammo, including .300 AAC Blackout loads. Other features include:

  • Low recoil and muzzle blast
  • 16" barrel of 4140 steel with 1-7.5" twist 5R rifling and 5/8"-24 threaded muzzle
  • 10" lightweight free-floated quad rail handguard with plenty of accessory mounting space
  • Comes "optic ready" - no front or rear iron sights
  • Low-profile gas block with integral Picatinny rail
  • Yankee Hill Phantom flash suppressor keeps flash signature to a minimum

The Smith & Wesson M&P15 .300 Whisper Complete Upper Receiver Assembly is drops onto any standard mil-spec AR-15 lower receiver, and you’re ready to shoot. You don’t even need to get new magazines - .300 Whisper/Blackout ammo uses standard 5.56/.223 AR mags.


Discontinued by the Factory

Product has been discontinued and no longer available.