.31 Pockets were Colt's biggest seller, lots were privately purchased and carried by ACW soldiers on both sides if they or their families could afford them. Also plenty of knockoffs made in Belgium and the Manhattan Arms co made bunches of Colt-like .31's. They were never a "military issue" caliber but probably could wager at least as many were carried as .36 and .44 revolvers. When things went hand to hand , 5 shots of .31 beat a clubbed musket or a knife. Also the little .22 and .32 Rimfire S&W's probably saw wider purchase and carry than any other private purchase handgun. I had read mainly for defense against other uniformed miscreants or local people who followed camps and stole stuff. .31 percussion was at least as powerful as a .32 Long which likely evolved from the .31 Percussion revolvers, through conversions.