Firing 3 or 4 of each powder increment would be an OCW test rather than a ladder test.
You don't need to go to 400 yards for OCW, 100 yards works fine.
Choose one test or the other. If you don't know the difference, it's harder.
If you fire five shots at 400 yards it takes five shots. If you fire five three shot groups at 100 yards it is fifteen shots. If you fire five four shot groups at 100 yards it is twenty shots. Tell me which one will find the best load the quickest with the least amount of wear on the barrel and wallet.
