I do agree with Mike that the original factory meaning for the "Model 1905" was the then new SQUARE butt.
However, the factory got away from that designation in just a few years, LONG before 1940, and considered them ALL 38 M&P's, WITH the option of round or square butt.
Many years ago, the precedent was set for defining variations by
mechanical changes when Neal & Jinks was first published in 1966. That's what collectors delight in- MECHANICAL VARIATIONS!!
If Mike wrote me a letter and said he just picked up an interesting 1902, I'd have no idea what he had, beyond it being a 38 M&P with a round butt.
If I wrote back to Mike and said I just picked up a 1905-3rd change
with a round butt, he might not like it, but he could pull out Neal & Jinks, and see EXACTLY which mechanical variant I had!
As I said, Mike is correct up to a point. He is correct in calling early round butts 1902's, and nothing else, IF he wants to do that.
However, there is NOTHING wrong with defining the mechanical changes as Neal & Jinks does, if one is interested in those mechanical changes. It's a workable system, and allows the rest of us to quickly and surely categorize a gun.
Below are the pics from Catalog D, issued in 1917, proving that the stooooopid factory could not tell a 1905 from a 1902 by this time. You'd almost think they were the same gun with different butt shapes
...........
