Jim. Thanks. Somehow, I don't think it is a Springfield barrel. It is a full 23.5 inches. If it had been set back, I would think that it would be shorter. The difference is only 3/8's inch. You'd have to set back a full half inch at least to rechamber to .308. I've seen the Springfield two groove barrels, and this one is different. If memory serves, the lands on the Springfield would look almost rectangular with a very shallow "U" on what would be the top, allowing for the curve of the bore. This rifle, if you were again looking head on into the barrel has one high side (the side that "bites" into the bullet to impart spin) but there is no other side. It tapers into the groove and looks like a shallow triangle. I guess I'm not explaining this very well. If I could draw a picture, you could see it right away.
I'll have to take the gun out of the wood tomorrow and see if that marking you mentioned is there. I'll say this though. The rifling is very very shallow. It hardly shows up on the slug.
Again, thanks for the help.
Paul B.