"In response, I put the silhoutte further out, and proceeded to do a tight group in the upper chest...one-handed. They went away."
That's how I normally deal with them, too.
It's always the ones who can't shoot who pull this crap.
I was taking guff some some assclown years ago for shooting a revolver.
"Eh, you only got six bullets (that was a signal of what we were dealing with right there). I'll still be shooting while you're reloading!"
When he pulled his target in from 10 yards it was apparent just WHY he needed high capacity magazines. Of about 30 shots, I'd say a good third of them were pure misses. The ones that did get into the kill zones were obviously random. The guy didn't have groups, he had patterns.
He was PLENTY pissed when I told him good marksmanship with 6 rounds is a lot cheaper than poor marksmanship with 30. But, after seeing my 12, all in the kill zone at a similar distance, he kept to himself, and that's what I cared about.