Bruce

I can guess here and say sometime after Marble Safety Axe became Marble Arms & MFG. in 1911. So I say very generally post 1911.

I have a No.2 exactly like yours here and it matches the dimensions given in a 1930s Marble trade catalog I have. The sight I pictured above that I think is older does not match all the dimensions for a No.3 in the 1930s catalog.

There is a transition period after 1911 where I think they used up the MSA marked sights and bases. It’s easier to see on the tang sights. The early sights have finer and smaller stamping in my opinion. I also think Marble Safety Axe sights have a higher luster blue than the later ones. I’m still learning about these things to and like I said, these are my best guesses. Maybe someone else has some observations.

Brad