Years ago when Lefever offered barrel sleeving services, I had them install a set of steel tubes in a PH Grade Parker mono-block; which mono-block had been made from the standard Parker Twist steel tubes. When completed, the barrels were rust blued; and as was noted above, only in really bright light could one see the barrel tube joints. This was an early No. 1 framed Parker; and if the balance of the Lefever restoration performed on that gun had been to the same quality level as the barrels, I'd not have traded it off.