Frank- I have never tried them on wood chucks but I know they have a heavier jacket, hence the following they have as a big game bullet. I am not sure if they would expand much on a varmint. You should consider the 140 Hornady A-max. This bullet has a very high BC and is extremely accurate. They seem to have a thin jacket and expand rapidly on wood chukcs. I shoot the 140 and 162 and they are devestating on varmints, very explosive. Hope this helps.