Re: Walther P22 or Ruger mkIII/
I donít believe in trading or selling my guns, but what you do is up to you. I would keep the Walther and grab the MK II.
I have a MK II 678GC and a MK III 512. The differences between the MK II and MK III are only 4: The MK III has a safety lock. It is a screw, that when activated, locks the safety. It can be safely ignored.
The MK III also has a loaded chamber indicator. It is actually slightly useful, but IMO, not a big deal.
The MK III has a thumb operated mag release, instead of the MK IIs bottom mag release. Which you prefer is up to you. I like the thumb release, but it was too short, so I drilled and tapped the button and screwed on a 1911 mag release extension. Works great.
The other feature of the MK III is the magazine safety. I donít care for this, so I replaced the hammer with a VQ MK II hammer and replaced the sear as a general thing. Trigger pull is now great, and no mag safety.