What kind of gun did Hernando de soto use?

Answer 1

It is unlikely that de Soto used any type of firearm, as the only type available back then were a harquebus, a sort of early musket. The harquebus was undeniably effective against any one opponent, but they are slow to load, heavy, and firing one is a complicated process involving the use of a wick which must be kept lit.

As de Soto was on horseback, his weapons would have been a sword, and probably a lance.

The lances were long wooden spears with iron or steel points on the ends, used to devastating effect on masses of native foot soldiers. In closer combat, a rider would use his sword. Steel Spanish swords of the conquistadors were about three feet long and relatively narrow, sharp on both sides. The Spanish city of Toledo was known as one of the best places in the world for making arms and armor and a fine Toledo sword was a valuable weapon indeed: the finely made weapons did not pass inspection until they could bend in a half-circle and survive a full-force impact with a metal helmet. The fine Spanish steel sword was such an advantage that for some time, it was illegal for natives to have one.