The RCBS X Die Full Length Set for .338 Win Mag is engineered for reloaders who want to eliminate the repetitive case-trimming cycle that eats up bench time. This two-die set pairs an X Die sizer with a standard seater die, combining innovative mandrel design with proven seating precision. The X Die's patented approach addresses one of reloading's persistent frustrations: case growth from repeated sizing. Instead of trimming after every cycle, you trim once—about .020 inch from maximum length to standardize your brass—then let the X Die's specially designed mandrel handle case growth for you.
How does it work? The X Die uses an expander ball and decapping pin integrated into a mandrel with extremely tight tolerances against the die's neck wall. As you size, the mandrel compresses case growth rather than allowing the case mouth to push the neck outward and thicken the wall. Your cases will grow a few thousandths in the first few cycles, then stabilize below maximum length and stay there—no more trimming, no loss of accuracy, no premature case life. If you already own a standard .338 Win Mag die set, you can purchase just the X Die sizer separately; this full set is the complete solution for a fresh .338 Win Mag reloading setup.
Built to RCBS's tight manufacturing tolerances, the X Die is built for volume reloaders who process dozens or hundreds of rounds per session and value consistency and efficiency at the bench. Pair it with quality brass, a good scale, and your favorite powder, and you're set for consistent, accurate .338 Win Mag ammunition without the trim-every-other-reload routine.
Key Features
- Two-die set includes X Die Full Length Sizer and Standard Seater Die
- Patented mandrel design eliminates need for repeated case trimming after initial setup
- Expander ball and decapping pin built into mandrel for one-step sizing
- Extremely close tolerances reduce case mouth thickening during repeated sizing
- Cases stabilize below maximum length with no discernible loss of accuracy or case life
- Ideal for high-volume .338 Win Mag reloading
Specifications
| Caliber | .338 Win Mag |
| Set Contents | X Die Full Length Sizer, Standard Seater Die |
| Die Type | Full Length Sizer with Integrated Decapping |
| Brand | RCBS |
Frequently Asked Questions
Do I need to trim my .338 Win Mag cases every time I reload with the X Die?
No. After your initial trim of approximately .020 inch off maximum length to standardize the case, the X Die's mandrel design manages case growth, allowing cases to stabilize below maximum length. Trimming is eliminated from the reloading cycle thereafter.
Can I use just the X Die sizer if I already own .338 Win Mag dies?
Yes. The X Die Full Length Sizer can be purchased separately if you already have a standard seater die for .338 Win Mag. This full set includes both the sizer and seater die for complete setup.
Will repeated sizing in the X Die affect case accuracy or lifespan?
No. Cases will grow a few thousandths of an inch initially, then stabilize below maximum length with no discernible loss of accuracy or case life, according to RCBS's design specifications.
What makes the X Die mandrel different from a standard sizing die?
The X Die features a specially designed mandrel with an integrated expander ball and decapping pin, manufactured to extremely close tolerances. This design reduces case growth caused by the case mouth contacting the mandrel, preventing neck wall thickening during repeated sizing cycles.
