The .450 Bushmaster exists at the intersection of two things hunters have always wanted: the handling and magazine capacity of an AR-15 and the terminal performance of a big-bore thumper. Developed in the early 2000s following a Tim LeGendre concept and commercialized by Hornady, the .450 Bushmaster pushes a .452-inch bullet at 2,200 fps from a 16-inch barrel. At 200 yards, it's delivering more energy than a .30-06 at the same distance. And because it's a straight-walled cartridge, it's legal in states and zones that prohibit bottleneck rifle cartridges in certain deer zones — a growing list that now includes portions of several midwest states.

Factory .450 Bushmaster ammo is expensive and sometimes hard to find. Handloading this cartridge is straightforward and the components are widely available. Here's how to do it right.

Case Preparation

The .450 Bushmaster uses a rebated rim — it's the same rim diameter as the .223 Remington, which is what lets it run through a standard AR bolt face with a modified upper. Brass is available from Hornady, Starline, and Winchester. Starline brass is the reloader's go-to: consistent, annealed from the factory, and available in bulk at reasonable prices.

Because this cartridge operates at moderate pressures (max SAAMI is 38,500 psi), brass life is excellent — expect 5–8 loadings per case with proper care.

Sizing

Full-length size for semi-auto use. Neck sizing only is not appropriate for an AR-platform rifle — you need full case body support and reliable feeding, which requires full-length resizing. Use a carbide die if available; it reduces friction without lube, though light lube on the case body never hurts to prevent stuck cases in a straight-wall configuration.

Trimming

Trim to the SAAMI trim-to length of 1.695 inches. Straight-wall cases grow more consistently than bottleneck cartridges and will need trimming more frequently — check every 2–3 loadings. Deburr and chamfer the case mouth after trimming to allow smooth bullet seating without shaving lead or copper.

Primers

Large rifle primers are standard for the .450 Bushmaster. CCI 200, Federal 210, and Winchester Large Rifle primers all perform well. For semi-auto use, consider CCI 200 or CCI 34 (mil-spec, harder cup) to reduce the risk of slam fires. This is a low-concern issue with the .450 Bushmaster's typical bolt speeds, but the harder cup provides insurance worth having.

Powder Selection

The .450 Bushmaster case volume is relatively small for the bore diameter, which means fast-to-medium-fast powders are the right fit. Suitable powders include:

  • Hodgdon H110 / Winchester 296: The classic choice for big-bore pistol-class and straight-wall rifle cartridges. Excellent consistency, meters well, and produces excellent velocities with heavy bullets. Start at 34.0 gr with a 250-grain bullet and work up.
  • Hodgdon Lil' Gun: Similar burn rate to H110, designed specifically for big-bore applications. Slightly better case fill in some configurations. A strong performer with 240–300 grain bullets.
  • IMR 4227: A traditional choice for this case. Slightly cleaner burn than H110 in some reports. Works well across the typical bullet weight range.
  • Hodgdon CFE BLK: A newer option that meters well and produces good velocities. Less temperature-sensitive than some alternatives.

Start 10% below published maximum loads and work up, watching for pressure signs: flattened primers, stiff bolt lift, or cratering around the firing pin hole.

Bullets for Hunting

The .450 Bushmaster fires standard .452-inch bullets — the same diameter as .45 ACP and .45 Colt. This means a wide range of projectiles designed for other applications can be adapted, though purpose-built hunting bullets perform best.

  • Hornady FTX 250 gr (used in LeveRevolution and factory .450 ammo): The benchmark hunting bullet for this cartridge. Excellent expansion at Bushmaster velocities, flexible tip prevents deformation in the magazine. Produces 1-inch groups from quality uppers.
  • Barnes TSX .452" 250 gr: Monolithic copper construction, excellent penetration, full weight retention. Ideal for deer and black bear. Requires slightly reduced loads compared to lead-core bullets — follow Barnes published data specifically.
  • Speer Gold Dot 300 gr: A heavier option originally designed for .454 Casull, it works well in the Bushmaster. More rainbow trajectory, but impressive terminal performance at close range.
  • Remington Core-Lokt 250 gr: A budget-friendly hunting option that performs well on whitetail and mule deer within 150 yards.

A Proven Starting Load

For deer hunting applications, this combination is a proven performer:

  • Brass: Starline .450 Bushmaster
  • Primer: CCI 200 Large Rifle
  • Powder: 35.5 gr Hodgdon H110 (work up from 33.0 gr)
  • Bullet: Hornady FTX 250 gr, seated to 2.250" OAL
  • Approximate MV: 2,150–2,200 fps from 16-inch barrel

Always verify OAL functions through your specific rifle's magazine and chamber before finalizing. AR-platform rifles can vary in chamber dimensions between manufacturers.

Performance at Range

The .450 Bushmaster is a 250-yard cartridge in practical terms — not because it can't reach farther, but because drop and energy loss make longer shots inadvisable on game. At 200 yards zeroed at 150 yards, you're looking at roughly 8–10 inches of drop. Know your trajectory and stay within ethical distances. Inside 200 yards, this cartridge is absolutely devastating on deer, feral hogs, and black bear.

For Oregon hunters, the .450 Bushmaster in an AR upper gives you a legal, reliable, hard-hitting deer rifle that uses the same lower you already own. The handloads cost a fraction of factory ammunition and let you tune performance to your specific rifle. Load it up.