I have 7 .22 WRMs: a Win 61M pump, a Savage 4M bolt, an 18 1/2" barrel for my G2 Contender, and a Savage Model 24 .410/.22WRM. All the rifles shoot the 40gr original Winchester ammo best except the G2, which shoots the 30 gr. Remington "green tip" ammo a lot better. Of my handguns, an S&W 651 4", a Colt New Frontier 6", and an S&W M48 6", they all shoot the 40 gr. Winchesters best except the 651 shoots CCI .22 WRF (Not WRM) 45 gr. better than any .22 WRM (I know it says not to shoot them in revolvers. I also know it is lawyerly BS....).
When I lived in NYS I killed a fair number of woodchucks with the Model 24's rifle barrel and with the S&W M48 and with a Ruger Bisley that I'd added a .22 WRM cylinder to. You need to hit them in the upper half of their body or head to kill them cleanly with a handgun in .22 WRM. For most of us, that means getting CLOSE! Much waiting and crawling....
The .22WRM in a rifle will kill them with any body shot at a reasonable range. In our part of NYS (northeast) woodchucks live in or very near the WOODS. They can't live in fields because most are plowed or hunted regularly. So most shots are 50 yards or less. I can't hit them reliably at 50 yards with a handgun, so spent some time "injuning up." Fun, but many tick bites..... With a rifle it is so much easier.