It isn't a matter of how hard it would be. It's a matter of how many they would sell.

I am very happy with my M69 and wouldn't buy a N-frame mountain gun myself. I think the M69 fills the role of a relatively light 44 better than a N frame mountain.

I hope S&W eventually makes one if 44 and 45 for those of you that do want one. It seems revolvers like the mountain gun and 610 come and go. My theory is there isn't enough demand for them to be a regular item but is S&W waits several years enough demand builds up to justify a small run of them.

I do wish I could have found a 617 without a full lug. Not sure if a L frame 22 would be considered a mountain gun but shaving a few ounces off would have been nice.