#1 spot goes to a 6lb H&R 12ga. Single shot, 3 1/2"er. I was squatting over a rain puddle and going to pattern it at 40 yds. The vicious little thing left a baseball-sized bruise on my shoulder and dumped my a-- into the water. I deserved that for thinking it was a good idea.
#2 was the famous Browning Stainless Stalker in 338 Win with a butt plate surface area just greater than that of a wedge. We named it the Flying Wedge.
#3 was a Rifles Inc 458 Lott with 500's.
All three made me apppreciate that famous philosopher Mike Tyson's quip : "everybody has a plan until they get hit in the mouth."