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Cartridge conversion

Posted: Mon Feb 03, 2025 10:21 pm
by 7000grain
The most common and recommended brass for converting to .450 Bushmaster is .284 Winchester brass. However, there are a few important considerations and alternatives to keep in mind:
.284 Winchester Conversion
.284 Winchester brass is the preferred choice for several reasons:
1. It has a rebated rim, which is necessary for the .450 Bushmaster cartridge.
2. The head diameter matches the .450 Bushmaster at .473 inches.
However, there are some challenges to be aware of:
• The neck wall thickness of converted .284 brass can be an issue, potentially requiring custom neck reaming.
• Some users report no problems with neck thickness, suggesting it may depend on individual chamber tolerances.
Conversion Process
To convert .284 Winchester brass to .450 Bushmaster:
1. Cut and trim the brass to 1.700 inches.
2. Chamfer the case mouth.
3. Resize using a .450 Bushmaster sizing die.
Some reloaders report success without any additional fire-forming process.
Alternative Options
While less common, other brass types have been considered for conversion:
1. 7.5x55 Swiss: It has the same head diameter as .284 Winchester but would require fire-forming due to its non-rebated rim.
2. 6.5-284: Another potential option, though less frequently mentioned.
Considerations
• Converting brass should only be done if commercial .450 Bushmaster brass is unavailable.
• Starline produces high-quality .450 Bushmaster brass, which is widely recommended for reloading.
• When converting brass, pay attention to neck wall thickness and overall cartridge dimensions to ensure proper fit and function in your firearm.