If you are shooting, best to wait until their backs are turned away from your line of sight. They move fast. I can’t imagine getting one with a pistol. I’ve gotten a few with a .22. Best success with a 20 gauge and birdshot.
The pistol was an ‘emergency’ situation. I didn’t have time to run get my 20 gauge, which for sure would have been ‘no miss’. My SIL was closer, so she was able to grab her pistol & get to me before the groundhog broke for the pole shed. The Collie was so funny ... not a hunting dog. The old Brittany Spaniel would have been all over that groundhog. I was yelling at the Collie “get it, get it” and she was barking & bouncing at it, feinting a bite (groundhog feinted back), then she’d look at me like ‘well, now what?’ I’d yell again ‘get it get it’ ... this went on until I had the pistol & could shoot it. My SIL was really shaken up - didn’t want the dog getting hurt & couldn’t shoot it herself.