.450 Bushmaster Complete Assembled Upper – Right Handed


Ejection Port Cover

Upgrade Handguard (Must Select One) *

Upgrade Muzzle Devise (Optional)


Gas Block *

Charging Handle

SKU: 450-CAU-RH Category:


As of June 2024, lead time for a complete upper to be shipped, is 5-10 days.

Complete ready to fire upper, with your choice of a 16″ or 18″ lightweight barrel.
Base model includes a 6061 M4 style upper receiver, black 4150 chromoly barrel, black A1 style flash hider, black gas block, complete bolt/carrier group, and charging handle.  You must select a hand guard option or have no hand guard installed in order to purchase this item.  All barrel muzzles are threaded 11/16.  Twist is 1:24.

Upgrade your upper with the Midwest Industries CRM M-Lok hand guard. Also available with upgraded heavy duty Tromix 7075 billet receiver, various muzzle attachments, engraved ejection port cover, etc.

Black chromoly barrels are externally coated with 2400 Series Bake-On GunKote.

With a Tromix 16″ light weight barrel, optional Midwest-Industries 9.25″ CRM M-Lok hand guard, and optional thread protector, the complete rifle weight on a standard M4 style lower is 5.49 pounds.

Pics shown with optional Midwest Industries CRM M-Lok hand guard installed.

All Tromix uppers are test fired prior to shipping.