BSA I have the Hornady bullet comparator set. If the headstamp bushings will fit the anvil, I can pick those up as well.
The headspace bushings will fit the same anvil. BSA appears to be using a 30 caliber bullet comparator bushing in his posted picture for some reason. Better than his trying to measure an air gap by feel though.
The Hornady headspace gauges are set to measure at the datum point at mid shoulder. The .420 diameter Headspace gauge is the proper one for your cases. If you have a .40 caliber insert, you will be close.
