.22!
About the same range as the .22 version. Remember, these are air PISTOLS, not rifles, so 10 yards is perfect, and 20 is LONG range for either caliber. Heavier pellet (appx. 14.3 in .22 caliber), makes a bigger hole. I have a HB22 and it is good for 20 yards and under on small game, with proper shot placement. The .177 may have a slightly higher velocity, resulting in a flatter trajectory, but the .22 pellets, IMHO, hit with much more wallop. If you were only going to plink at cans or feathered game, the .177 pellet pistol with Crosman or RWS pointed pellets would be fine. But for rats, squirrels, etc., the .22 hits harder.