Item Number: TR-450K16F24Q
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Detailed Description


.450 Bushmaster

The .450 Bushmaster is a large bore, straight-walled cartridge that is compatible with a standard AR receiver.  It has higher supersonic velocities than most other big-bore .45 caliber AR cartridges but is bot typically used as a subsonic round.  The .450 Bushmaster is ballistically equivalent to the 45-70 and legal for hunting is states that require straight-walled cartridges.


 Chamber  .450 Bushmaster
 Feed Ramps  Purpose Built .450 Bushmaster Specific Barrel Extension
 Finish  Matte Bead-Blasted Stainless
 Gas Block Seat  .875" Diameter by .900" Length - Dimpled for Set Screw
 Gas System  Carbine Length
 Length  16"
 Material  Stainless Steel, Type 416R, Barrel Grade
 Muzzle Threads  11/16" x 24
 Profile  Recon Tactical - Fluted
 Rifling  1:24, RH, Six Groove, Precision Button Rifling
 Weight  28.7 oz.


Build Kit Includes:

  • 16" Barrel
  • Complete Bolt Carrier Assembly (Nickel Boron)
  • Adjustable Gas Block
  • Gas Tube, Straight
  • Whisper® Suppressor Interface or Q-Comp 
  • Blue Print for Upper Receiver Modification


  Barrel Schematics

The .450 Bushmaster is an impressive caliber for hunting and defense but in order for the large, powerful cartridge to properly function in an AR certain steps must be followed.

1.) Our .450 barrels are chambered and set to minimum headspace using a PTG chamber reamer.  This is the latest generation, improved Bushmaster reamer and designed to accept properly sized brass only. After firing, your empty cases may require trimming depending on your chamber dimensions and load.  For all sized cases and factory and reloaded ammunition, we suggest using a case/ammunition gauge to check your ammunition’s overall dimensions.

2.) Since our build kits and rifles are set to minimum headspace to allow for slight headspace growth over time, you may have failures to completely chamber or close for several rounds after building your upper.  As your chamber burnishes and bolt and locking lug surfaces mate together your Bushmaster will start to feed as designed.  This is a very powerful cartridge and we have engineered it to have very tight tolerances for long-term safety and reliability.  Make sure you use plenty of light oil on all bolt surfaces when breaking in your upper.  This will help the locking surfaces mate with your barrel extension.

3.) Make sure you use the proper Extra Power Action spring shipped with your kit. When adjusting your gas block ensure that you have enough gas for proper function.  Test your gas block by adjusting your flow to allow lock back on an empty magazine.  If your gun locks back on an empty magazine after 3 single-loaded shots it is reliably locking back. 

4.) We only use 5.56 Lancer magazines for best reliability in .450 Bushmaster.  We do not recommend P-Mags in .450 Bushmaster.

5.) Gas block installation.  Our barrels have one dimple for the rear gas block screw. When installing the gas block make sure the rear screw is tight in this dimple before tightening the front screw.  You can drill an extra dimple for the front screw with the proper drill for extra security.  Before permanently attaching your block with loctite or rocksett ensure that the barrel gas port and the gas block port line up. If your gas port is out of alignment with your block your rifle may short stroke. 

6.) Gas block adjustment.  Follow the instructions with the adjustable block to tune your gas pressure.  This is more easily accomplished with the handguard off the rifle. Remove the front adjustment lock screw and adjust your gas valve screw until your bolt locks back on empty with your lowest powered ammunition.  Test your gas block by adjusting your flow to allow lock back on an empty magazine.  If your gun locks back on an empty magazine after 3 single-loaded shots it is reliably locking back.  When tuned to your satisfaction, lock the gas valve screw with the small locking screw.

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