L.E Wilson Expanding Mandrel - .337" (338-cal)

The L.E Wilson Expanding Mandrel is designed to be used together with the L.E Wilson Expanding Mandrel Die to prepare new brass cartridge cases for the seating operation, by expanding the neck to slightly under bullet diameter.

New brass cartridge cases are often damaged when shipped in bulk, and are usually manufactured with necks tightly sized. To ensure a consistent inside neck diameter on your new cases, it is advisable to run new brass cases over an expanding mandrel to properly prepare them for their first firing. With correct and consistent neck tension you can expect a more consistent seating depth and shot performance.

Additional interchangeable mandrels are sold separately, to suit each bullet diameter. Only one die is required, mandrels are quick and easy to exchange.

Compatible with standard reloading presses using 7/8-in threads.

The L.E Wilson Expanding Mandrel Die (with the appropriate mandrel) only expands the case neck to slightly under bullet diameter; it does not re-size any other part of the cartridge case.