R&R;'s and the Winchester Ledger|Winchester Rifles|Forum|Winchester Collector

I, like more of you,  have seen quite a few rifles that of the letterable era that have been altered.  Some have interesting things about them that got me to thinking.  Lets say a gun letters as 16″ trapper and was built in the late 1890’s.  But, now the gun is a standard 20″ carbine.  But, in addition to the different barrel and associated parts, the rifle is now proof marked on both the barrel and receiver. 

If Winchester did the work, would the R&R be listed in the ledger regardless of when the work was done?   If the work was done, say, in the 1920’s.  Would the factory have recorded the work in the original ledger?