Bill,
You asked in an above post about the effectiveness of .177 versus .22.
I actually got a good deal of experience with .177, .20, and .22 on ground squirrels.
Terminal effectiveness was directly proportional to caliber.
The bigger the caliber, the faster they went down.
Here's a true story of how I got my experience.
Hawkeye Wizard
GROUNDSQUIRREL GOLF
I hired Bob to work with me at Rock Island Arsenal.
It didn’t take long for me to find out that we had much in common. We both loved guns ---any guns --- in fact, anything that launched a projectile.
We shot bows, airguns, and firearms together. We attended gun shows together. We drove gravel backcountry roads reducing the ground squirrel populations.
One day, Bob mentioned that a golf course near Eldridge, Iowa had a serious ground squirrel problem.
The little rascals were wreaking havoc on the course. Their holes and mounds were everywhere.
Golfers often complained about losing balls down ground squirrel holes.
Bob approached the golf course manager, offering our professional services. An agreement was reached.
The golf course owner agreed to provide us with a cart, two score cards, and free cold pop. We agreed to reduce the ground squirrel population at NO COST to the course.
The owner did specify two restrictions.
We couldn’t “work” on weekends because the course was crowded with golfers.
And, we couldn’t “work” on Thursdays because it was lady’s day. Heaven knows, we wouldn’t want to offend the sensibilities of any lady golfers.
Regularly, Bob and I would show up at the course. We’d load the rear of a cart with a variety of cased air rifles.
Then we’d pick up scorecards and Cokes, and head out on the course.
We’d take turns driving. When one of us spotted a ground squirrel, the driver would angle toward the prey, not driving directly at him, but rather, closing the distance at an angle.
When either of us felt he could make the shot, he’d say “Close enough.”
The driver would stop and the optimist would take a shot. If he missed, the other one would get a shot.
On our scorecards, headshots counted for 3 points, body shots for 2, anything that got into it's hole before expiring counted 1, and misses were a 0.
Our best day eliminated fifty three of the little hole diggers.
The course owner was grateful for our help. So were the golfers.