Nutria are funny little beasties. Tough. But I honestly don't know what ammo would be good or bad - never shot one or known anybody that has. Plenty of my friends down Texas way use .17 HMR on groundhogs to great effect. Typically a nutria is gonna be about twice the size of a groundhog, but if natural predators are scarce groundhogs can reach their size or even slightly larger (up to 30 pounds. Yeah, I know, that's a hell of a groundhog).
I'm guessing a good varmint load in .17 would work acceptably well, but that is pure gut feeling. Got nothing to really back that up. If I was going after them the first thing I would reach for would probably be my 24" heavy-barreled AR15. But that would make quite a mess.
EDIT TO ADD:
Apparently the cops down in N'awlins hunt them with .22 LR, and have good success:
http://www.nola.com/news/index.ssf/2008 ... _17th.html
Sounds like sheer numbers are on the side of the nutria, for now.
I'm guessing a good varmint load in .17 would work acceptably well, but that is pure gut feeling. Got nothing to really back that up. If I was going after them the first thing I would reach for would probably be my 24" heavy-barreled AR15. But that would make quite a mess.
EDIT TO ADD:
Apparently the cops down in N'awlins hunt them with .22 LR, and have good success:
http://www.nola.com/news/index.ssf/2008 ... _17th.html
Sounds like sheer numbers are on the side of the nutria, for now.