I have a heavy barrel single-shot Sako 6 PPC that is new and unfired. The serial number reads: Sako PPC B 502. The materials that came with the rifle are marked L461, although the action has the bolt shroud of an A1. I'm curious about the serial number. I know that some PPCs had an A XXX number, and I'm wondering what the B 502 number signifies. I'm assuming that it is an A1 action, but wondered whether the serial number might be suggesting something else (like an S491, for example). Any thoughts on this? One reason I ask is that the action-screw spacing seems to be just slightly longer than the 6.25" of my other Sako 6 PPC, a repeater, which is clearly an A1.