.450 Bushmaster

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.450 Bushmaster
.450 Bushmaster (left), .223 Remington (right)
Type	Rifle
Place of origin	United States
Production history
Designer	LeMAG Firearms LLC
Designed	2007[1]
Manufacturer	Bushmaster Hornady
Produced	2009–present[2]
Specifications
Parent case	.284 Winchester
Case type	Rebated, straight
Bullet diameter	.4520 in (11.48 mm)
Land diameter	.4420 in (11.23 mm)[3]
Neck diameter	.4800 in (12.19 mm)[3]
Base diameter	.5000 in (12.70 mm)[3]
Rim diameter	.4730 in (12.01 mm)[3]
Rim thickness	.0540 in (1.37 mm)[3]
Case length	1.700 in (43.2 mm)[3]
Overall length	2.260 in (57.4 mm)[3]
Case capacity	59.5 gr H2O (3.86 cm3)
Maximum pressure (SAAMI)	38,500 psi (265 MPa)
Ballistic performance
Bullet mass/type Velocity Energy 250 gr (16 g) SST 2,214 ft/s (675 m/s) 2,722 ft⋅lbf (3,691 J) 260 gr (17 g) AccuTip 2,180 ft/s (660 m/s) 2,744 ft⋅lbf (3,720 J) 250 gr (16 g) FTX Hornady BLACK 2,200 ft/s (670 m/s) 2,686 ft⋅lbf (3,642 J)
Test barrel length: 20 in (508 mm) Source(s): Lynx Defense[4]

The .450 Bushmaster (11.48x43mmRB) is a rifle cartridge developed by Tim LeGendre of LeMag Firearms, and licensed to Bushmaster Firearms International. The .450 Bushmaster is designed to be used in standard M16s and AR-15s, using modified magazines and upper receiver assemblies.