Ken the "slower burning" powder was also a problem for the Mexican Armies at the battle of San Jancinto. I checked with Wikipedia and this is what I found. The gun powder from was probably made back in Spain or from old european recipes that were called "serpentine" that were't really very relible as for as the burning process neededs for gunpowder. " Serpentine (apparently a reference to Satan[14]) was a dry-compounded black powder used in fifteenth century Europe and in other regions surrounding the Mediterranean Sea. It was difficult to ignite properly in canon. Wooden plugs had to be used to prevent the mixture from physically separating during firing. Twentieth century experiments showed that serpentine packed with tight wooden plugs was capable of producing muzzle velocities comparable to that of later (corned) gunpowder. Serpentine also had the tendency to separate in components during transport, thus it had to be remixed before using, raising clouds of explosive dust—a risky proposition in combat conditions. Later gunpowder was mixed in a water or urine medium, dried, then cut. This was called corned powder, and it was more powerful (it had more propulsive energy per unit of mass), but also burned more rapidly, making it unsafe in old guns. By 1500 corned powder became the standard propellant for new guns, but older, potentially unsafe guns were used with serpentine into the seventeenth century"