Reply To: sizing die
It’s a CZ barrel on a .25 Vulcan. Using a caliper and a 20x jeweler’s magnifying glass I tried my best to make sure the caliper is on the top of the grooves 180 degrees apart, and next that its also within the grooves the same way. The measurements: 0.246 (6.25mm) lands and 0.252 (6.4mm) grooves.
I measured a .25 (6.35mm) JSB 25.39gr pellet head and skirt. The skirt measured 0.255 (6.50mm) and the head 0.249in (6.34mm).