I was thinking on the davis, one thing they did, which was smart I think, was build their gun based on CENTER fire, then they used an offset firing pin in the rimfires, the result I think is a lot more versatile design overall.
The one I had was a 22 magnum, the only problem with it was that it did not have enough firing pin impact to reliably fire some brands of 22 magnum ammo, this is not however an UNcommon problem with 22 magnum handguns from what I have read.
With the lower barrel I once put 5 shots in the X ring of a 25 yard slow fire pistol target, at 25 yards even :-)...the upper barrel shot equally as accurately, but about 18" higher at 25 yards...the lower bbl shot right to point of aim at 25 yards, overall for the price of the gun I was really surprised by accuracy and poi.
Bill