W,
I'll be very honest, a faint demarcation line does not really bother me. I build these guns to shoot them and to hunt them, not for re-sale. On my .450 #2 NE, 9.3x74R, and .303 British doubles, where I screwed the barrels into the mono-blocks, after polishing and rust bluing, the seam is virtually invisible. In many cases, until I have pointed it out to a viewer, they have not even been aware that there is a seam there.