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.
|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|
|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|
Build Kit Includes:
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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|Product ReviewsClick here to review this item|
|This kit is good in many aspects. There are a couple annoying issues however that were uncharacteristic of Wilson Combat's typical quality. PROS - All of the parts in the kit are of high quality. The barrel was almost perfect aside from the issue I describe below with the gas hole. The WC branded gas block is essentially an SLR Sentry 8 adjustable gas block which is regarded as one of the best on the market. The bolt carrier group is super slick and beautiful along with being properly staked. The rapid thread brake is decent quality but can't be timed correctly with the provided shims. CONS - 2 Issues 1. The barrel was almost perfect until the person who drilled the gas hole and dimple put them slightly off center from the flutes and Wilson Combat logo. In a perfect scenario, when they would drill the gas hole and dimple for the gas block, they have the gas hole perfectly centered between the flutes at 11 and 1 o'clock. The hole isn't perfectly lined up. 2. The Rapid Thread muzzle brake is made for silencers and the forward blast diverter. Because of this it comes with shims vs the traditional crush washer to avoid a cant of the brake which could lead to a baffle strike. The problem is they include a shim kit with only 3 shims and a washer to protect damage of the shims. 2 of the shims (silver) are identical in size, and 1 shim (red) is slightly smaller than the 2 small stacked shims. When I hand tighten the brake with the washer as instructed, the brake bottoms out at about 1 o'clock. So I need to go approximately 165-170 degrees to clock perfectly straight. Using any variation of the shims and I end up clocked incorrectly. The closest I get is back to between 12 and 1 o'clock with all 3 shims. That's not going to work. The kit talks about yellow, black, and green shims all of which are not included in the kit, nor can they be purchased from Wilson Combat directly. And to further compound the issue and my frustration, the only shim kit they sell is the one that came with the 450 BM kit. That kit is out of stock. So essentially I can't finish the build until I locate a shim kit for 11/16"x24 brakes. I can only find one manufacturer (Badger Ridge) that sells this type of shim online. I ended up ordering 2 of the kits because there is a slight chance that one kit alone might not have the correct variation of shims to time the muzzle brake correctly. Bottom line is this. The kit has everything packaged to ALMOST finish a gun. Add the rail, receiver set, furniture and gas tube and you are ALMOST ready to go. I think it's fair to expect the gas hole to be drilled perfectly centered with the flutes and the shim kit to include all of the shims needed to time barrel and brake especially given the fact that both of them came from Wilson Combat in the kit. For that reason I've dropped the rating from 5 to 3 stars. Minus one for each of the 2 issues that WC should address.|
|- Andrew Haight, MI|