Perazzi Type 4 step rib barrels w/thinwall chokes from an MX8. Fits all square monobloc Type 4 guns (MX8, MX12, MX2000, etc). Barrels measure 81cm long or about 31.75" and weigh 1.630kg (marked 1.680kg). Comes with a choke wrench and choke case, along with 6 thinwall chokes in: Improved Cylinder, Light Modified, Modified, Improved Modified, Full, and Extra Full. Barrels are in excellent shape, with only very light bluing wear, virtually all covered by the forearm wood. It has a white front bead and is drilled and tapped for a mid-bead, though does not currently have one in (blanking screw in place). $3300, shipped.
Your barrels appear to be old type three that had the barrel lug modified to fit type four iron. Is that correct? the serial number shown goes back forty years, or so.
Could be. It is definitely a Type 4. Not sure if the lug was replaced or modified by a previous owner.