Unfortunately, Herb Parsons and Tom Knapp are dead but the guy who took over for Tom is probably faster than Mayer with a pump gun. I'll grant these guys aren't as accomplished at reading targets as Mayer but for speed I'm pretty sure any of them as well as numerous others will do as well or better.
Even Mayer seemed to recognize this in himself as I recall he carried a Beretta O/U on his cart to use for certain presentations. I'm not downplaying Mayer's shooting skill overall but that he is not some rare maestro using a pump gun.
