Bill if youre mainly punching paper with it I'd go the 177 route. 500 pellets are less than half the cost and trust me, you will be shooting a LOT of pellets with this gun. I'm also finding that the CO2 lasts a bit longer on the 177 for some reason.
Another thing I'm noticing is that the 22 slows up a tad if you shoot rapidly, the CO2 cooling effects it and not the .177.
The 22 hits very hard at 20yards despite the fact that it's going more than 100fps slower than the 177.
I use an 18 wheeler trailer rubber mud flap as a backstop. The 22 bounce off it at 22 yards and the 177's drill into it, but the sound of the energy when the 22 hits makes you sit up and pay attention .
I have not taken both my 22 and 177 out to longer ranges. I know the 177 is great out to 40 yards and beyond for birds. For rabbit / tree rat, I'd draw the line at around 45 yards (and it'll have to be a head shot)
I'm not sure about the .22 yet though. At 45 yards the 177 will still go through 1/4" ply wood.
All I can say for sure is that the 177 shoots flat from 20 yards out to 40..so it's easier for me to hit stuff
So that coupled with the pellet cost would put me in the 177 camp right now.
I'll be trying the 22 out in the next few weekends at longer ranges I'm sure.The 850 Resource
I'll let you know.