By the way, field accuracy with air rifles is typically pathetic when compared to a .22 LR firearm. If you're shooting in a laboratory setting, the airgun may be theoretically superior, but when you factor in the realities of shooting. like wind and range estimation, the air guns are a real joke. Do not let anyone try to BS you otherwise. For example, if you're zeroed at 25 yards you will need to know how much to hold over at 35 yards. If you get it wrong, you miss your squirrel. Of course, this assumes you can judge the difference between 25 yards and 35 yards very accurately.
That said, I do "long range" rifle practice at about 35 yards by shooting at spent rifle brass. It's quite challenging as a target game. It's like shooting a 30-06 at 250 yard targets in the wind. The only thing missing is mirage and down-range wind effects.