The very early rifles came out of the Savage factory with six groove barrels. And, whilst it shouldn't have happened, a few with two groove barrels slipped through the net as well. I have owned both Savage & Maltby rifles with two groove barrels (from new) that were converted to 4T's. I do wonder if that is the reason why many Savage rifles are found with replacement UKmanufacture barrels on them - because they were noted to have two groovers & so were earmarked for 'upgrading' with new production five groove examples.