Recently built a 22BR with a 7 twist to shoot the 90 grain bullets. Since building the rifle I haven't been able to find Bergers but have shot quite a few pdawgs with the 90 gn Sierra's. It isn't really explosive at longer ranges but it does hammer them real hard. I don't know how many rounds are typically shot during a string at Groundhogs but on Prarie Dogs the high velocity rounds heat the barrel so fast they have to be allowed to cool after 5 shots or so, which seriously limits their usefulness. A good friend has a 22-250 AI that shoots very well, but it heats the barrel so fast its practically useless.