Hi Gary-

Based only on serial number I suspect that the rifle is genuine.  You are right that the 264 WIN MAGNUM Featherweight-Westerner didn’t appear in Winchester’s own catalogs until 1963, but they were available by at least mid-1962.  For example they are listed for sale in the 1962 Gopher Shooters Supply catalog and their mid-1962 print ads.  It makes sense that rilfes assembled in 1962 would, in part, be built using receivers made in 1961.

Roger Rule reported that (3116) Featherweight-Westerners were shipped in total.  Looking at the M70 survey, to date we have (294) serial numbers recorded (9.4% of the total produced).  Based on this sample, (2%) were made using 1960 dated receivers, (20%) were made using 1961 dated receivers, (73%) were made using 1962 dated receivers, and only (3%) were made using 1963 dated receivers.  So it appears that nearly all of them were built in 1962…

Interestingly, of the small number from 1963, there are (6) recorded in 300 WIN. MAGNUM!!!  None of the earlier Featherweight-Westerners are in that chambering, suggesting that Winchester actually did make a handful of 300 WIN MAGNUM Featherweights at the tail end of production, i.e. that they’re not all fakes… .  

Best,

Lou