
Availability: In Stock
The RCBS Full Length Die Set for .338-378 Weatherby Magnum is a two-die reloading set engineered for shooters developing ammunition for this powerful magnum cartridge. If you're handloading for a .338-378 Weatherby—whether you're chasing elk at extended range or pushing heavy bullets downrange at the bench—this die set gives you the precision and control to produce consistent, safe rounds. RCBS has built their reputation on quality reloading dies, and this set follows that tradition with robust construction and tight tolerances.
The Full-Length Sizer Die is the foundation of the set. It resizes your fired cases to SAAMI minimum cartridge dimensions, ensuring consistent headspace and case body dimensions from load to load. The die includes an integrated Expander-Decapping Unit that removes the spent primer and opens the case neck to accept a fresh bullet. Vented construction prevents air trapping and excess lubricant buildup—details that protect your brass from damage during sizing. For a magnum cartridge like the .338-378, that precision matters: tight headspace control keeps pressure curves predictable and performance repeatable.
The Seater Die handles bullet seating and features a built-in roll crimper that secures the bullet in place as you seat it. This means you can establish consistent bullet seating depth and apply a crimp in a single stroke, streamlining your reloading process and improving round uniformity. Both dies are standard 7/8"-14 thread, fitting any standard reloading press.
If you're serious about .338-378 Weatherby handloading—whether you're a precision rifle competitor, a long-range hunter, or an enthusiast who demands the best from your magnum—this RCBS die set delivers the tools to load ammunition to exact specifications, every time.
| Product Type | Two-Die Full Length Reloading Set |
| Caliber | .338-378 Weatherby Magnum |
| Dies Included | Full-Length Sizer Die with Expander-Decapping Unit; Seater Die with Roll Crimper |
| Die Thread | Standard 7/8"-14 |
| Manufacturer | RCBS |
Yes, if your press accepts standard 7/8"-14 thread dies. This is the industry standard, used in virtually all single-stage and progressive presses. Confirm your press manual if you're unsure.
This full-length sizer resizes the entire case body to SAAMI minimum dimensions, ensuring your fired cases return to factory specifications. Full-length sizing is the safest choice for magnum cartridges and is essential if you're loading for a rifle you may lend or sell, or if you're using brass from multiple sources.
The Full-Length Sizer Die includes an Expander-Decapping Unit that handles primer removal as part of the sizing stroke, so you're ready to begin reloading with the dies as supplied.
Yes. This set is designed for the .338-378 Weatherby Magnum and will help you produce safe, consistent ammunition for any lawful use, including hunting, target shooting, or range work.

SKU: 115830714 • Weight: 1.3oz





Availability: In Stock
The RCBS Full Length Die Set for .338-378 Weatherby Magnum is a two-die reloading set engineered for shooters developing ammunition for this powerful magnum cartridge. If you're handloading for a .338-378 Weatherby—whether you're chasing elk at extended range or pushing heavy bullets downrange at the bench—this die set gives you the precision and control to produce consistent, safe rounds. RCBS has built their reputation on quality reloading dies, and this set follows that tradition with robust construction and tight tolerances.
The Full-Length Sizer Die is the foundation of the set. It resizes your fired cases to SAAMI minimum cartridge dimensions, ensuring consistent headspace and case body dimensions from load to load. The die includes an integrated Expander-Decapping Unit that removes the spent primer and opens the case neck to accept a fresh bullet. Vented construction prevents air trapping and excess lubricant buildup—details that protect your brass from damage during sizing. For a magnum cartridge like the .338-378, that precision matters: tight headspace control keeps pressure curves predictable and performance repeatable.
The Seater Die handles bullet seating and features a built-in roll crimper that secures the bullet in place as you seat it. This means you can establish consistent bullet seating depth and apply a crimp in a single stroke, streamlining your reloading process and improving round uniformity. Both dies are standard 7/8"-14 thread, fitting any standard reloading press.
If you're serious about .338-378 Weatherby handloading—whether you're a precision rifle competitor, a long-range hunter, or an enthusiast who demands the best from your magnum—this RCBS die set delivers the tools to load ammunition to exact specifications, every time.
| Product Type | Two-Die Full Length Reloading Set |
| Caliber | .338-378 Weatherby Magnum |
| Dies Included | Full-Length Sizer Die with Expander-Decapping Unit; Seater Die with Roll Crimper |
| Die Thread | Standard 7/8"-14 |
| Manufacturer | RCBS |
Yes, if your press accepts standard 7/8"-14 thread dies. This is the industry standard, used in virtually all single-stage and progressive presses. Confirm your press manual if you're unsure.
This full-length sizer resizes the entire case body to SAAMI minimum dimensions, ensuring your fired cases return to factory specifications. Full-length sizing is the safest choice for magnum cartridges and is essential if you're loading for a rifle you may lend or sell, or if you're using brass from multiple sources.
The Full-Length Sizer Die includes an Expander-Decapping Unit that handles primer removal as part of the sizing stroke, so you're ready to begin reloading with the dies as supplied.
Yes. This set is designed for the .338-378 Weatherby Magnum and will help you produce safe, consistent ammunition for any lawful use, including hunting, target shooting, or range work.
SKU: 115830714 • Weight: 1.3oz
