I have not. But, since a 22 is essentially a plinker and a target pistol, I'd just bypass the DA and use it SA.
Friend has one of these for sale. Double action trigger pull is horrendous. I called Walther in their new digs and spoke with a not very well versed gentleman. He said the double action trigger pull was about 20 pounds and there was no way to lighten it. He said the single action trigger pull was "quite light at about 5 pounds". I'm not going to buy it like that. Anybody try to lighten that trigger pull?
I have not. But, since a 22 is essentially a plinker and a target pistol, I'd just bypass the DA and use it SA.