In the sporting world a .458 Win Mag. Three rounds. Did not like it much.
Was at the range shooting my .220 Swift off a bench next to a guy sighting-in who apparantly had more money and a larger bore gun than he had knowledged of shooting. He saw at one target change that I was shooting what he though were some real tight accurate groups so he asked me if I would run a few rounds through his .458 so he could see what he was doing wrong while sighting-in. I put three shots down range and saw that it was sighted-in just fine but a bit high at 100 yrds. He said he wanted it to be zero/zero at 100. I adjusted 1 MOA down for elevation and said he should be fine. He asked me to shoot 3 more rounds to see if it was zero'd. I said "sir, you've been more than generous allowing me to fire $$$ through you fine rifle, but I must respectfully decline as I think it's time now for me to go have my shoulder x-rayed"