I've poured water through barrels, made heat wave diverters, taped target tubes to scopes and devised other even more embarrassing solutions to hot barrel heat waves. I ordered a battery powered = 2 D fan from Home Depot-delivered to a close store, for $6.88; picked it up this morning and shot using it today. It sits on a plastic ammo box or ??, makes no noise, and the barrel heat waves are gone-no more waves through the scope. The batteries, 4 per pkg, cost more than the fan. Zowie! joe b.
http://www.homedepot.com/s/battery%2520operated%2520fan?NCNI-5