For the Experts on the Forum, What does Custom Built Winchester on the rib mean?

Custom Shop gun? Maybe, depends on when it was manufactured, before 1968, there was no Custom Shop, only Custom Built shotguns.
As to value, thats established when money changes hands.
The particular M21 is not a catalogued Model with standard choices of engraving but a Custom Order I have never seen.
I have had a number of dealings with Tony and own a CSMC Grand American Baby Frame M21 in 28 ga and a Fox DE Special 16 ga made for me as well as other CSMC models made for me. A number of individuals who fancy themselves experts and collectors, put their noses in the air when they are mentioned.
If one wants an original Winchester M21 410, and particularly that gun then you have to pay the price and that price is $20K. A CSMC Baby Frame M21 which will weigh about 5# 13 oz starts at around $20.

Last edited by Dick_dup1; 12/09/20 12:31 PM.