Just thought I'd pose a quick question to the experts about stocks and recievers.

Found an M1 with an open box SA cartouche on the stock behind the grip with an "F" under it. The reciever is a Winchester and there are a number of SA stamped parts.

Would it be realistic for a winchester reciever to find itself in a post war SA rebuild? Any idea what the F is? Thank you and sorry if I'm not making any sense.

In 1948 a lot of M1 Garands were updated, rebuilt and put into storage regardless of manufacture.  The Army just considered it an M1 regardless of who made it.

The theory on the open box SA stamp was that it was created from the WWII stamps with the inspectors initials ground off.  The letter below belonged to the person who inspected the rifle post war.  Unfortunately, those names have been lost to time.

Nobody cared the manufacture as it went through rebuild. Win is just rarer due to lower original production numbers, only something like 12% as many as SA manufactured.

The F is the inspectors initial.

Thank you for the prompt responses, much appreciated.

As part of the original contract there was contracted spare parts.  There were also later stand alone spare part contracts.  So the military had spare parts of different brands through the years.  

It is entirely possible and likely  to see a mix of parts from a rebuild.

Even new manufactured rifles came off the line with mixed parts for different reasons.  An Ordnance program of parts interchangeability was one reason, they were verifying interchangeability so Springfield, H&R and International Harvester would swap parts.  There were also times when the government would provide parts for factory builds, H&R rifles with SA  bolts, op rods and trigger assemblies.   A bunch of NIW guns returned from loan to the Greek military were literally in foil wrap, never used and showed such part content mixes.  It rewrote what the collectors thought they knew.  A lot of guys previously had “correct” as built guns but swapped the parts for same name brand to make them “correct”. Oops.

Wait until you get into M1 Carbines OP.

Talk about a hodge podge of part manufacturers going to different carbine manufacturers............................