A star gaged barrel with a drawing #C 64112 The number indicated a National Match rifle assemble . A star gaged barrel could have been purchased C64111 barrel only I believe you have a star gaged barrel Standard issue barrels are P proofed on the bottom Your is on top . I think the barrel is a bit late for the receiver .I did note the rear sight base windage scale is polished A plus The rear base may have came with the barrel, Need to see pic of the sight base cross pin .