My Savage No.4 Mk1* has 2 groove rifling and it worried me for a while as I only had a few rounds of MK7 to shoot and could not find any flat based ammo or bullets to reload. I need not have worried as it turned out that with PPU boat tail reloads it is my second most accurate rifle, after my Enfield Envoy, out to 600 yards. I believe it all to do with the condition of bore in particular close to the chamber where gasses can escape round the tail of the bullet (boat tail) and destabilise it.