I'm a big fan of the MKII pistol and the .22 magnum cartridge but I don't see this happening.

 

Probably wouldn't be nearly as successful as the Ruger 10/22 Magnum.

 

I suspect the action would have to be a little longer. There is likely much more in redesign necessary than is obvious.
On the other hand, I have a Keltec .22 WMR pistol - it works every time, is accurate, and has a much better than decent trigger.

 

I have looked into the Keltec 22 SMR, I see it has good reviews but I have not handled one yet. I like that it holds 30 rounds!

 

The cartridge would not fit in the existing action and wouldn't sell enough in volume to warrant a redesign.

 

I understand the action will need to be longer with a heavier bolt and return spring, mag well would have to be bigger. Am I missing something? I think the rest of the parts could interchange.
17HRM would be another cool chambering.

I agree probably couldn’t sell enough to warrant the tooling.

 

If Ruger offered a MK IV in .17 HMR with a 10" bbl., drilled and tapped for a scope, I would probably be a customer - not that I need it, but my sales resistance might be negative numbers.