I found this old post by Mike from New Zealand. His pictures show his IP with 2-43 dated Rock-Ola barrel.
The barrel letters match the style of the one I've been questioning (bottom one above) dated 3-43.
RMC must have changed the style of the font/stamp at some time.
Mikes has a R stamped on the front of the gas cylinder.
https://www.milsurps.com/showthread....8&daysprune=-1
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