The .177 vs .22 question will always come down to weighing the compromises.
If it’s strictly for targets, .177 is the obvious choice for the shot count, and both the variety and economy of pellets.
If it’s strictly for hunting and pesting, shot count usually gives way to making a bigger hole and maximizing energy delivered to the target.
When it comes to PCP pistols, both shot count and energy are pretty anemic compared to a rifle so the compromises seem to encroach pretty severely into the decision making.
Knowing that you will be spending far more time shooting targets, .177 is the baseline assumption, then see if you have a sufficiently convincing reason to “need” .22. I can relate to your goals. They align very well with my own. For a relaxing practice session in the back yard, I’m not going to pick up a .22 that gets 20 shots per fill nearly as often as a .177 that gets, say, 35 shots per fill. Refilling is an annoying interruption to an activity that should be enjoyable. Sure, I could tune the .22 to get that many shots but now I’m lobbing mortar shells at my 40 yard target. Or if I can tolerate the low velocity because I’m keeping my shots inside of 20 yards, I could instead downtune the .177 to get 55 shots.
But there are those times I want to grease a gray squirrel. In .177, I prefer to stick with brain shots. Above 10fpe, I have no reservations taking heart/lung shots but 99% of the time I will wait for a brain shot or just pass on the opportunity. In .22 cal, I’m perfectly happy with a vitals shot. Lungs do comparatively worse at extracting oxygen when they have 50% bigger holes.
Lastly, I have to be honest with myself about how well I can shoot a pistol. With an accurate PCP rifle, I know I can put 10 out of 10 pellets in a squirrel’s kill zone at 50 yards. With a pistol, I haven’t yet reached that level of confidence even at 25 yards. Again, 10 for 10...I get absolutely disgusted with myself if I injure an animal with a poorly placed shot. So if my range is limited too severely by my abilities, I’m going to want the .22 so shot placement isn’t as critical.
With all that said, my current go-to pistol for both practice and small game is a .177 tuned to a very modest 6fpe. Why so low? Well it was a bit by accident. I adjusted it to 13fpe straight away and picked it up from time to time to whack a chipmunk or squirrel. After a while I realized it just wasn’t getting used much. A misbehaving regulator made me tear into it. I reconfigured the Bellevilles for a lower setpoint and tinkered with a few tunes before ending up at one producing about 60 shots at 6fpe. That’s when I realized, wow, it doesn’t have to shoot 800fps to be fun. I started picking it up all the time.
Then I added the folding shoulder stock and changed from a 4x scope to a 9x with AO and saw my groups shrink from 1in at 25 yards down to 1/2”, and some as small as 1/4”. That’s good fun on a lazy Sunday afternoon. I can put in a couple of short sessions, 20 or 30 pellets, and not have to refill. Somewhere in there, smash a chipmunk off the stump near the bird feeder.
Maybe that will give some perspective
