skilled, creating the "fitting ledge" is a more complex operation than not having such a feature. Therefore, why would a counterfeiter go to the trouble to create the "ledge" that is NOT original when it would be easier to leave off the "ledge" and thereby look more original?
The "fitting ledge" is an original feature, dependent on the vintage of the stocks. My earliest Python and Officers Model Match both have the "ledge."
Based on my personal collection, I believe the "fitting ledge" was discontinued in 1955 or 1956. However, that said, it may be a vendor-specific feature where one vendor used it, and another did not. (I am assuming that Colt did not make stocks in-house Post-War. That may or may not be a valid assumption.)
(Apologies to anyone offended by my "delivery.")