Calling all ammo boot experts

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Would anyone happen to know when these boots were made? I am thinking late 30s or early 40s but have no experience with these boots. Research leads me to believe the early ones sometimes lack the horseshoes and steel tips as reinforcement measures, but I haven't seen many. I was hoping someone would recognize the stamps on the outer soles. Unfortunately no apparent markings on the inner sole, nor size.

Thanks

[Grimebox]

In my opinion dating ammo boots can be quite difficult, especially when you factor in post service use and resoling or the removal or addition of hob nails. All I can say is that I have not seen any with the circular mark on the bottom before. It reminds me of the WW2 Indian manufactured approval mark/stamp as found on uniforms

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Thanks for your reply. That's actually quite interesting. Here is such a stamp. Wondering if it's something similar.
Is there a way of defining the stamp? Might try going over it with a pencil but not sure if it will help. Would the 2 and the O right above the heel have any particular meaning?
Thanks