I have a 177 krait here that is crazy accurate with AA express. Produces hole not much larger than the calibre itself at 37yds (furthest I can go at my wind free barn, rested - obviously)
I the past with another accurate 177 (rapid) these were also very tight groups but I head the head shot runners I've mentioned on a previous post (some years ago, I think) - one was a rabbit with was between eye and ear with obvious pass through and brain matter emerging from the exit wound. Maybe the pellet was deflected due to lighter weight.
I'm gonna give 177 a chance to redeem itself next time out. It'll be a krait with the pard 008 mounted. Shots will be max distance or 30yds (dictated by perm) against rats. I have no desire to re-live the rabbit experience with any live quarry.
Recently I've been running the pard on my uragan compact in 22 with a massive success rate.