The exact .450 Bushmaster bullet diameter is 0.452 inches, which converts to 11.48 millimeters. While .450 Bushmaster ammunition is available with different bullet weights, the cartridge’s nominal projectile diameter remains exactly the same across all factory loads. This measurement refers specifically to the width of the bullet itself, which differs from the internal dimensions of the barrel. Specifically, a standard .450 Bushmaster firearm utilizes a narrower bore diameter of 0.429 inches and a groove diameter of 0.452 inches to ensure a tight gas seal upon firing.
450 Bushmaster Bullet Diameter
| Specification | .450 Bushmaster |
| Nominal Bullet Diameter | 0.452 inches |
| Bullet Diameter In Inches | 0.451″ to 0.452″ |
| Bullet Diameter In Millimeters | 11.45 to 11.48 mm |
| Groove Diameter | 0.452 inches |
| Bore Diameter | 0.429 inches |
| Typical Bullet Weights | 200 gr to 300 gr |
| Case Length | 1.700 inches |
| Overall Cartridge Length | 2.260 inches |
| Maximum Pressure (SAAMI) | 42,500 PSI |
What Is The 450 Bushmaster Bullet Diameter?
The .450 Bushmaster bullet diameter is the physical width of the unfired projectile seated in the cartridge case. Developed by Tim LeGendre of LeMag Firearms and adopted by Bushmaster Firearms in 2007, the cartridge was engineered to bring big-bore, thumping performance to the standard AR-15 platform. The cartridge utilizes a true .45-caliber bullet measuring 0.452 inches across, allowing it to share projectiles commonly manufactured for pistol rounds like the .45 ACP and .45 Colt, but driven at much higher rifle velocities.
450 Bushmaster Bullet Diameter In Inches
According to the official Sporting Arms and Ammunition Manufacturers’ Institute (SAAMI) specifications, the .450 Bushmaster bullet diameter in inches is standard at 0.452 inches. Factory-loaded jacketed and monolithic copper hunting bullets are manufactured strictly within the 0.451″ to 0.452″ range to ensure smooth chambering and optimal engagement with the barrel’s rifling.
450 Bushmaster Bullet Diameter In Millimeters
For those using metric measurements, the .450 Bushmaster bullet diameter in mm ranges from 11.45 mm to 11.48 mm. Because 1 inch equals 25.4 millimeters, multiplying a 0.452-inch bullet by 25.4 yields exactly 11.4808 mm, which rounds cleanly to 11.48 mm.
450 Bushmaster Bullet vs Bore Diameter
A common point of confusion is the difference between the bullet’s width and the barrel’s internal dimensions. The .450 Bushmaster bore diameter is 0.429 inches. The bore diameter measures the distance directly across the “lands” (the raised portions of the rifling inside the barrel). The unfired .450 Bushmaster projectile diameter (0.452″) is deliberately wider than the bore so the rifling can firmly bite into the bullet jacket, imparting the stabilizing spin required for accuracy.
450 Bushmaster Groove Diameter
The .450 Bushmaster groove diameter measures 0.452 inches. The groove diameter measures the distance across the deepest cuts inside the rifled barrel. When the 0.452-inch bullet is fired, it swages into the barrel and completely fills the 0.452-inch grooves. This creates a tight pressure seal that traps the expanding powder gases directly behind the bullet, preventing velocity loss and maintaining high muzzle energy.
450 Bushmaster Bullet Weights
While the cartridge diameter is fixed, you can select vastly different projectile masses depending on your application. The .450 Bushmaster bullet weight typically ranges from lighter 200-grain and 250-grain polymer-tipped loads up to heavy 300-grain jacketed hollow points or solid copper bullets designed for hunting big game like deer, hogs, and bear. Changing the weight alters the bullet’s length, trajectory, and recoil, but the diameter remains fixed at 0.452 inches.
Bullet Diameter vs Other Cartridges
Shooters must be careful when comparing caliber names, as cartridge names frequently do not match the physical measurement. Here is how the .450 Bushmaster compares to other straight-walled and big-bore rounds:
| Cartridge | Bullet Diameter | Diameter In mm |
| .450 Bushmaster | 0.452″ | 11.48 mm |
| .45 Colt | 0.452″ | 11.48 mm |
| .45 ACP | 0.452″ | 11.48 mm |
| .350 Legend | 0.357″ | 9.07 mm |
| .308 Winchester | 0.308″ | 7.82 mm |
| 5.56x45mm NATO | 0.224″ | 5.70 mm |
Notice that the .450 Bushmaster shares an identical 0.452-inch bullet diameter with handgun rounds like the .45 ACP and .45 Colt, but operates at a significantly higher rifle pressure to deliver dramatically increased range and velocity.
Bullet Weight
Ammunition manufacturers produce several specialized loads for the .450 Bushmaster, primarily tailored for mid-range hunting in states with straight-walled cartridge regulations.
| Bullet Weight | Example Load | Bullet Type | Advertised Velocity |
| 200 grain | Hornady Custom | FTX | 2,200 fps |
| 240 grain | Hornady XTP Mag | JHP | 2,225 fps |
| 250 grain | Remington Performanceed | Managed Recoil / PSP | 2,150 fps |
| 300 grain | Federal Power-Shok | JSP | 1,900 fps |
Velocities represent typical factory test barrel data, generally from a 16-inch or 20-inch rifle barrel.
Dimensions
To understand how the cartridge safely fits into AR-15 and bolt-action platforms, here are the complete SAAMI-verified .450 Bushmaster dimensions:
| Dimension | Measurement |
| Bullet Diameter | 0.452″ |
| Groove Diameter | 0.452″ |
| Bore Diameter | 0.429″ |
| Case Length | 1.700 inches |
| Overall Length | 2.260 inches |
| Base Diameter | 0.500 inches |
| Neck Diameter | 0.478 inches |
| Rim Diameter | 0.473 inches |
| Maximum Pressure (SAAMI) | 42,500 PSI |
.450 Bushmaster vs .350 Legend
Because both cartridges are popular choices for straight-walled cartridge deer hunting jurisdictions, shooters frequently compare the .450 Bushmaster and .350 Legend.
Despite both being straight-walled rifle cartridges designed for modern sporting rifles, they have distinct differences:
- Bullet Diameter: The .450 Bushmaster utilizes a massive 0.452-inch bullet, whereas the .350 Legend uses a narrower 0.357-inch bullet.
- Recoil and Power: The .450 Bushmaster operates at a higher pressure (42,500 PSI) using much larger powder charges, resulting in heavier recoil and significantly greater terminal energy at medium ranges compared to the milder .350 Legend (which operates at 55,000 PSI in a much smaller casing).
- Magazine Capacity: Because of its larger case head and base diameter (0.500 inches), a standard 5.56 AR-15 magazine typically holds fewer rounds of .450 Bushmaster (usually single-stacking to about 4 or 5 rounds), whereas the .45-ACP-based case dimensions of the .350 Legend allow closer to standard magazine capacity.
450 Bushmaster Bullet Diameter: Exact Measurement
The exact .450 Bushmaster bullet diameter is 0.452 inches, or 11.48 millimeters.
While the actual projectile measures 0.452 inches across, it is forced through a barrel with a 0.429-inch bore diameter and a 0.452-inch groove diameter. This intentional sizing ensures the bullet squeezes tightly into the barrel’s rifling grooves. This physical engagement creates a reliable gas seal behind the projectile, preventing the 42,500 PSI of high-pressure expanding gases from blowing past the bullet while stabilizing it for accurate downrange hunting performance.
FAQs
What is the bullet diameter of 450 Bushmaster?
The nominal bullet diameter is 0.452 inches.
What is 450 Bushmaster bullet diameter in mm?
In metric measurements, the diameter translates to 11.48 mm.
Is 450 Bushmaster a true .45 caliber?
Yes. The actual projectile measures 0.452 inches across, making it a true .45-caliber bullet.
What is the bore diameter of 450 Bushmaster?
The barrel’s internal bore diameter (measured land-to-land) is 0.429 inches.
What is the groove diameter of 450 Bushmaster?
The barrel’s internal groove diameter (measured groove-to-groove) is 0.452 inches.
What bullet weights are available for 450 Bushmaster?
Factory loads typically range from 200 grains up to 300 grains, with 250-grain loads being a popular standard for deer and hog hunting.
What is the case diameter of 450 Bushmaster?
The case is straight-walled with a slight taper, featuring a base diameter of 0.500 inches that narrows down to 0.478 inches at the neck.
How does 450 Bushmaster bullet diameter compare with 350 Legend?
The .450 Bushmaster fires a much wider 0.452-inch bullet compared to the .350 Legend’s 0.357-inch bullet.