Size expander plug .002 0ver bullet size. For a 400 dia. bullet use a .402 x .398 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
40 Pistol Expander Sizes
40Cal (P) .402 x .398, 40Cal (P) .403 x .399, 40Cal (P) .404 x .400