I don't know, while I'm no expert in this area, something doesn't look right to me. Seems too thick or heavy.
I think your best bet is to have it tested with an x ray spectroscopy machine. That should tell you the composition and you can compare that to what was actually used in that era. Maybe send it to Peter's heat treat. Thay have one of those machines and test for unknown metals. Give them a call and see what they say
I would think any amount of aluminium, manganese or nickel and maybe even silicone would be a dead giveaway for a reproduction