1928 Pigeon trap with stainless steel barrel
https://www.gunsinternational.com/guns-f...un_id=100715897

In the 1920s, stainless steel was referred to as 18/8 to indicate the percentage of chromium and nickel; now referred to as Type 304 and with a maximum of .08% carbon. Still no data about the Winchester stainless.
The industrial standard ultimate tensile strength is 73,200 psi/yield 31,200 psi. Rockwell B hardness is 70/ Brinell 123.

Lots of images of M12s with stainless barrels, but I have yet to find an early M12 with Standard Ordnance Steel

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