.22 is either for training (when the best choice is a conversion unit) or for foraging, when the best choice is somethiung with a silencer mounted on it, or something that is very handy as you fish, hike, etc. For such purposes, the HP22, Smith 2214, M21 Beretta, Walther TPH are all pocketable. The HP22 and M21 are far easier to suppress, the 2214 is about impossible to suppress, unless you are willing to settle for a mere 1.5" of rifling. then you could counterbore and thread 3/4" of the muzzle.
Tph has too short a barrel for the counterbore technique to work. It requires a longer barrel, as do the other 2. GunsNStuff sells a threaded barrel for the M21, and Phoenix sells a 5" barrel for the HP, which is easily cut to 3 3/4" and externally-threaded. The TPH requires a longer barrel, and removal-replacement of that barrel requires a frame support, so you don't collapse it in the vise, a torch, with which to heat the "horseshoe" frame collar, which then expands enough to let you use a mallet to drive the barrel backwards, out of its frame-mount. HUGE PITA.