Details
Bulldozer SBR Ready 5-Inch 1-16 .45 ACP AR-45 Freefloat M-LOK Pistol Full Build Kit, SBR Ready
This is an AR-45 pistol full build kit chambered in .45 ACP, centered on a 5-inch slim profile 4150 CrMoV steel barrel with a Parkerized finish, a 1-16 twist rate, and a 37-64x28 thread pitch specific to the .45 ACP bore diameter. The AR-15 billet upper receiver for pistol calibers anchors the front end with a design purpose-built for the pistol caliber AR platform. The 4-inch Ace Series freefloat M-LOK handguard wraps the barrel along the forend and keeps the front end compact and clean on this pistol-length build. A PCC AR bolt assembly for .45 ACP and an M4 Mil-Spec charging handle complete the upper side. The lower completion package covers the full internal lower component group, a Mil-Spec heavy-duty 6-position buffer tube, an AR-15 9mm carbine buffer, a standard carbine recoil spring made in the USA, and a full rear hardware group. This kit ships without a brace, leaving the final rear end setup to the buyer. Lower receiver not included.
Key Features
- .45 ACP chambering, 5-inch slim profile 4150 CrMoV steel barrel, Parkerized finish
- 1-16 twist rate, 37-64x28 thread pitch
- AR-15 billet upper receiver for pistol calibers
- 4-inch Ace Series freefloat M-LOK handguard
- PCC AR bolt assembly for .45 ACP
- AR-15 M4 Mil-Spec charging handle
- Complete Mil-Spec AR-15 lower parts kit
- Mil-Spec heavy-duty AR-15 6-position buffer tube
- AR-15 9mm carbine buffer
- Standard AR-15 carbine recoil spring, made in the USA
- AR-15 M16 Mil-Spec receiver end plate
- AR-15 carbine castle nut
- SBR Ready
- AR-15 .45 ACP Birdcage muzzle brake, manganese phosphate finish, 37-64x28 thread pitch
- Black 5-8-inch crush washer
Perfect For
- AR-45 pistol builders who need everything above the lower receiver for a compact .45 ACP build
- Shooters pairing this kit with an existing AR-45 lower receiver
- Builders selecting their own brace or stock for a custom AR-45 pistol or SBR platform
Upper Assembly
The AR-15 billet upper receiver for pistol calibers is the correct upper receiver choice for the AR-45 platform, designed around the dimensional requirements of pistol caliber operation that differ from a standard AR-15 upper receiver. The 5-inch slim profile 4150 CrMoV steel barrel brings a Parkerized finish and a 1-16 twist rate to the .45 ACP chamber, threaded at 37-64x28, a thread pitch specific to the .45 ACP bore diameter. The slim profile keeps the front end lean and well-suited to the compact pistol-length layout of this build. The 4-inch Ace Series freefloat M-LOK handguard wraps the barrel from the upper receiver along the forend, keeping the overall front end compact and purposeful with M-LOK slots along the handguard body for accessory attachment.
Bolt Assembly and Charging Handle
The included PCC AR bolt assembly is specific to the .45 ACP chambering and is the correct bolt choice for this platform. A standard AR-15 bolt carrier group is not compatible with the .45 ACP AR-45 platform, and this bolt assembly addresses that platform-specific requirement directly. The M4 Mil-Spec charging handle pairs with the bolt assembly inside the upper receiver to complete the upper interior and finish the front end of the build.
Lower Completion Components
The complete Mil-Spec AR-15 lower parts kit covers the full internal lower component group, including the fire control group, magazine catch, bolt catch, and all associated pins and springs. The Mil-Spec heavy-duty 6-position buffer tube, AR-15 9mm carbine buffer, and standard AR-15 carbine recoil spring made in the USA form the buffer system at the rear of the lower, matched to the pistol platform and the blowback operation of the .45 ACP AR-45 build. The AR-15 M16 Mil-Spec receiver end plate and AR-15 carbine castle nut lock the buffer tube down at the rear of the lower receiver. The brace or stock selection is left entirely to the buyer, keeping the final rear end open for a custom setup.
SBR Ready
This kit ships without a brace and is intended for builders selecting their own final rear end setup. The Mil-Spec heavy-duty 6-position buffer tube and complete lower hardware are included, but the brace or stock is sourced separately by the buyer. The final rear end configuration is setup dependent and determined by the component the buyer selects.
Muzzle Device
The AR-15 .45 ACP Birdcage muzzle brake with a manganese phosphate finish threads onto the 37-64x28 muzzle end of the barrel, a thread pitch and caliber designation specific to the .45 ACP bore diameter. The included black 5-8-inch crush washer seats at the barrel shoulder and completes the muzzle hardware for this kit. The .45 ACP specific Birdcage muzzle brake is the correct muzzle device choice for this bore diameter and thread pitch combination.
Follow safe handling and manufacturer instructions. Ensure compliance with all applicable federal, state, and local laws. Ships without a brace. Do not attach a stock unless compliant with applicable laws. Lower receiver not included.
