Yes, I can do barrel work and have, and I enjoy it. My most challenging effort to date was fitting a new 16MM LW .20 cal. barrel to a Gamo CFX. Came out pretty good, even if I do say so myself, although I still need to tweak the leade a bit.
It's interesting to note that the 160 has NO orings sealing the barrel, and there's only about 1 1/2" extending into the breech, and 1/2" of that is cut off for the loading trough. I don't have the QB yet, I'm still putting together my shopping list for this project, and haven't completely made up my mind which model to use for this conversion. I'm leaning toward the Deluxe, just because of the longer LOP, but then I remind myself I'm trying to clone my 160 and lean back toward the base model
Your accuracy numbers would be more than satisfactory, this is going to be a hunter, and I generally limit my range to 40 yards or less, depending on what I'm shooting. Where did you get your barrels, and mostly out of curiosity, what do you think of the .25 in this application? I'm almost certainly going to stay with .22, but I've been playing with a .25 lately, and it's kind of intriguing. Gotta run, later.