RCBS Full Length Die Set for .378 Weatherby Magnum (378WBY)

The RCBS Full Length Die Set for .378 Weatherby Magnum is purpose-built for reloaders working with one of the most powerful magnum cartridges in hunting. This two-die set handles the critical jobs of resizing and seating—the foundation of safe, consistent ammunition. If you're loading for a .378 Weatherby rifle, you need dies that respect the cartridge's specs and deliver repeatable results.

The full-length sizer die resizes cases to SAAMI minimum dimensions, the standard that ensures safe headspace and reliable chambering. It simultaneously de-primes spent primers and expands the neck to properly accept bullets. The die is vented to prevent trapped air and excess lubricant from damaging your cases—a detail that separates quality reloading dies from the rest. Headspace is maintained at minimum tolerances so the sizing process won't inadvertently change case body length, which matters when you're handloading precision ammunition.

The included seater die handles bullet insertion with a built-in roll crimper that secures the bullet as it seats, all in one step. This efficiency without compromise is what you expect from RCBS—a company that's been refining reloading dies longer than most of us have been shooting. Whether you're loading for long-range hunting, handgun hunting at distance, or just maximizing factory ammunition performance, this set gives you the tools to work safely within published specifications.

Key Features

• Full-length sizer die resizes cases to SAAMI minimum dimensions
• De-priming and neck expansion in one operation
• Vented die prevents air trapping and lubricant damage
• Headspace held to minimum tolerances for consistent case length
• Seater die with integrated roll crimper for bullet retention
• Two-die set sized specifically for .378 Weatherby Magnum

Specifications

Frequently Asked Questions

What does a full-length die set include?

This RCBS set includes two dies: a full-length sizer die with expander-decapping unit, and a seater die with bullet seater plug and integrated roll crimper. Together they handle resizing, de-priming, neck expansion, and bullet seating in the steps required for safe reloading.

Will this die set work with my .378 Weatherby Magnum rifle?

Yes. This set is specifically dimensioned for .378 Weatherby Magnum and resizes cases to SAAMI minimum specifications for that cartridge, ensuring safe headspace and reliable chambering.

What does the venting in the sizer die do?

The vents in the full-length sizer die prevent trapped air and excess lubricant from building pressure inside the die, which can damage cases. It's a design feature that protects your brass and extends the life of your ammunition.

Does the seater die crimp the bullet?

Yes. The seater die includes a built-in roll crimper that secures the bullet during the seating operation, so you seat and crimp in one step.