Tay
.22 is better for killing pests, because of the heavier caliber. Neither will kill instantly, but .22 is better.

kaptainfelix
Depends what pests. If your talking about rats try rat poison (anticoagulant, metal phosphide or hypercalcemia) If its sport you're after, shoot them by all means but poison is far more effective

Poppy
For outside for varmint control, better stick to the air pistol not .22( too much velocity, and projectile can travel a mile). Of course use in city limits can be illegal. Make sure aim is good, nothing in background, to hit or damage, ie use extreme caution, and a cool head at all times.

OkieRoadhunter
What do you mean by using two pistols? You can only shoot one at a time. If you're wondering if you should get .177 or .22, and you want two guns, get one of each.

RUGERIZMISTICNESS
Dude, I've shot squirrels all week with my .22 air rifle, and haven't retrieved any off them because they retreated to their holes before dying. I used a Gamo shadow express with 16.2gr Gamo master point-I really would have thought this to be more potent- especially at the 15 yards I was at.

C_F_45
It would depend on the "pest" and just how good a shot you are. IMO better would be. Crosman 2250 The 2250 will give you a 550fps .22 vs the HB22 at 460fps Crosman 1377 1377(600fps) vs 525fps for the HB17 It would still depend on what "pest" , and you have to match the pellets to the game, for best results.

J Kirsch
As C_F_45 said, a lot depends on what the "pest" is. Mice? English Sparrows? Starlings? Rats? (This matters because the impact energy needed can range from a low of 2 ft-lbs for mice and English Sparrows, to a high of 5 ft-lbs for rats.(1)) If I'm doing the math right (and if Crosman's velocity numbers are accurate with medium weight hunting pellets), the HB 22 theoretically gets 6.6 ft-lbs of muzzle energy and the HB 17 theoretically gets 4.9 ft-lbs of muzzle energy. (Note the use of the word theoretically. Airgun manufacturer's often use light weight pellets to increase the claimed velocity of their airguns. That means that you may have less power than the above figures indicate since the velocity with medium weight hunting pellets would be lower than the figure I plugged in.) Of the two pistols you mentioned, the HB .22 would be a better gun for pest control since it has more power. The biggest issue I can see for doing pest control with an air-pistol is accuracy constraints. Basically the kill zone for most pest species ranges between .5 and 1-inch in diameter. Since you don't have a lot of margin for error in power with the larger "pest" species, shot placement becomes critical. If you can't keep all your shots in a .5 - 1-inch circle at 20 yards you're likely to wound a lot of animals instead of create clean kills. Because of that, I'd encourage you to get an air-rifle which would have more power and better accuracy. If you're on a budget say something like the Crosman 2100, Daisy 22SG, Crosman Phantom, or Crosman 2260. If money's not an issue, something like the RWS 34 or Benjamin Discovery...