Size expander plug .002 0ver bullet size. For a .337 dia. bullet use a .339 x .335 expander plug. this will give you .002 clearance to start your bullet and .002 neck tension.
Additional information
Weight
.25 lbs
Dimensions
1 × 1 × 1 in
338 Rifle Expander Sizes
338Cal (R) .339 x .335, 338Cal (R) .340 x .336, 338Cal (R) .341 x .337, 338Cal (R) .342 x .338, 338Cal (R) .343 x .339