Wilson Expanding Mandrel .337" Caliber Sizing Die
Prepare new brass cases for consistent neck diameter and reliable bullet seating. Wilson expanding mandrel die with stainless steel construction fits standard 7/8" reloading presses. Caliber .337".
Wilson Expanding Mandrel Sizing Die for .337" Caliber
This specialized reloading die addresses a critical but often overlooked step in ammunition preparation: properly conditioning new brass cases before their first firing.
Why Use an Expanding Mandrel?
New brass cases frequently arrive with inconsistent neck dimensions due to shipping and handling. An expanding mandrel die ensures uniform neck diameter across all your cases, which directly translates to:
- Consistent neck tension on your bullets
- Uniform seating depth from round to round
- More predictable ballistic performance and tighter shot groups
Key Features
- Interchangeable mandrels allow you to use the same die body for different calibers
- Stainless steel construction resists corrosion and provides years of reliable service
- Cutout viewing window makes case alignment and depth adjustment straightforward
- Expands neck to slightly under bullet diameter for proper tension without over-sizing
- Standard 7/8" press compatibility works with virtually all modern reloading presses
- Wilson manufactured lock nut (.225" thick, .270" height, 1.250" OD) ensures secure die positioning
What's Included
One mandrel for .337" caliber. Additional mandrels for other calibers are sold separately, making this an economical choice if you reload multiple cartridges.
This die represents sound reloading practice—a small investment that pays dividends in consistency and performance.
