I actually just got rid of a 17HMR and thats the only one ive never felt guilty about giving up. It was useless to me.
I also got rid of a wore out early 80s ish Charles Daly semi auto and I regret that too and never thought I would, the other and biggest regret is my AR15.
Those are the only guns ive ever got rid of, and never again will I do it again. Like I said I would get rid of the 17HMR again but thats the only thing.