I usually go for head shots with the .17m2, but I have used the aquilla SSS ( 60 grain ) on lots of grouse, with body shots. Every one dropped right away, with very little meat damage. But, the Aquilla's were not shot out of an NEF, you'd have to check for accuracy. An old timer once told me that in his opinion, for body shots, a .22 short is best. Perhaps (??) the concept is the same, a slower bullet that stays in the body longer, before exiting, might (??) result in more shock. I know this goes against the Ft/Lbs concept of killing power.
Or, maybe try a blunt-nose bullet, like the CCi SGB, for more shock, and probably less meat damage then the HP's.
Mark