Charlie,

The similarities and differences are probably explained as a combination of the numbers of machines and the number of stages used during the production. Where workstation #1 machine (and operator) is going to hold the blank in his right hand, the guy on the #2 workstation of the same stage is going to hold it in his left hand. They then both go into a bin for the next stage of cuts (enter the Right hand" vs "left hand" differences again).

Add in things like machine/tool/bit/sandbelt wear across time (and part replacements) and you will undoubtably find variations. This was all hand manufactured on machines 70 years ago. You only have 4 "time markers" identified here - RMC/Q-RMC/2 rivet/4-rivet. Its not like they are serialized and you can track the exact changes over time.

Remember that morse code operators can identify a message sender just by the individual characteristics of the sender's code pattern. I am sure you could also use the same technique to identify the craftsmen (and women) who made these hand guards - where the cut was started and shere it was stopped.

Today was are all used to products being EXACTLY like next one coming out of the plant - cars are exactly the same, TV's, computers, etc. With computer-controled production, any differences are so minute that we can not detect them.

You, my friend, are seeing individual craftsmanship at work. Enjoy it - you will never see it again in today's world!

Thanks for the challange!

Ed