I haven't really tried any long distance, 25 meters is the usual shooting distance (roughly 27 yards). I dont think you'll get much precision at more then 50 meters but maybe I'm being picky, you'll certainly hit a full size siluette at 50 meters but the wind is likly to be factor and the short barrel isn't going to help the bullets velocity. I got one photo of the H&K currently available; [link]
Okay then. I just make up my own weapons in my stories and stuff. Sometimes I use existing ones as inspiration, but most of the pistols I draw use 13 mm bullets. I don't own any guns, sadly, so I don't know that much about them anyway.
It is an adjustable palm rest, by adjusting height and angle to the shooters hand the pistol can be held comfortably and securly without having to maintain a hard grip. The grip is manufactured by Rink, I found this page which explains some of the features of the grip; [link]