That gun is in my estimation 100% Winchester made by Classic Doubles. The style of floral engraving, the bluing finish, the rib shape, between barrels porting and the gold birds are very late model, last run before the switchover occurred without the Winchester name.
I saw a fellow at a skeet shoot several years ago with a set of 4 non-winchester CD 101 skeet grades(12-20-28-410) and they all had that same matte like finish and the ribs were vastly different than what you have. Love that POW grip on yours. I have a buddy with a really late run CD made Winchester Model 23 in 20ga with the identical gold birds and it too was part of a 4 gun serial # matching set in the 4 gauges.
A few years back a fellow I used to hunt with picked up a very late model, again last run 101 20ga (non-pigeon) with the identical floral pattern engraving for sale on gunnutz. It was very interesting to put it alongside my mid-80's made 50th Anniversary DU and compare the similarities and differences.
From what I have seen most have never seen these late model runs because Winchester was ending the line so there was nowhere near the number distributed of the earlier models. When Winchester started having CD produce their double guns they had them made to the identical specification as they were when first introduced and over time started switching aesthetics up a bit. You can see the difference easily in hand between a mid-70's 101 Pigeon or other of the higher graded guns especially in the wood when compared to a mid 80's 101. The colours were much lighter and figure offered in pigeon and other higher grades was vastly different(improved) as were subtle differences like forend shapes, recoil pads, rib styles, engraving depth and patterns and even the markings and style of Winchokes (flush mount) which on earlier models were not available. Earlier models had the classic narrow external knurled end if the gun was optioned with screw chokes. Many still had fixed chokes. Not to say they aren't out there but I've never seen a CD made 101 with fixed chokes. What you have in my opinion based on your pictures is 100% a last run 101 by CD for Winchester. I would not be the least bit surprised either that just like when they ended the Model 12 and the SX1 that many of these guns got assembled in the custom shop from leftover production parts hence the "it doesn't look like any Winchester I've seen in that grade".
