I second Tim the Slugman. I used to do a lot of set and trotline fishing along the Sabine and Trinity rivers. I always carried a S&W Kit gun for snakes. Shotshells are good for Cottonmouths and copperheads within 3 to 6 feet. If the snakes were farther than that I usually ignored them. While I can usually hit a snake at that distance with a solid or hp .22 the operable term is "usually". I perferred the shotshell as being more positive. I usually loaded with 2 shotshells and 4 solid points with the shotshells next in rotation to fire first. The solids were for gar that I occasionally pulled in and if I needed them I would rotate the cylinder to pull them up. Snakes up close and personal are about all the .22 shotshell is good for IMO. YMMV.
OldSalt
OldSalt