A 22lr at 100+ fpe is more powerful than most 22 caliber airguns. But my 22 and 25 caliber P35s are both at about 32 fpe and only three of 22 squirrels taken with them has failed to have an exit hole. So what does the other 68+ fpe of a 22 lr do? It isn't going to help kill the squirrel. Maybe a little flatter trajectory. Within 40 yards, my PCPs are pretty flat trajectory but at longer ranges, the 22lr would be and advantage. For small game I would argue there isn't much difference. For bigger game where more penetration is needed then the 22lr (or a more powerful PCP) will have an advantage. The most practical way to increase fpe in an airgun is to go up in caliber. But at the same fpe, the smaller caliber will have more penetration. Bigger holes tend to kill more quickly too. It all depends on what you want to do.