Thanks Russell. I wonder if the problem was sort of in between the two (serpentine and corned) in that their corning process was 'unsophisticated' so their result turned out, at least partially, like the old serpentine powder. When I was a kid, we had a neighbor kid that would buy the components at the hobby shop and make his own which must have been essentially the serpentine powder. It produced more smoke than 'explosion' and looked pretty cool with our green army men. ;-) The Mexican powder apparently still had the problem it did at San Jacinto (1836-37?) a decade later in the Mexican war where the Americans observed their solid shot cannonballs skipping along the ground toward them, slowly enough that they could dodge them. It appears the quality problem continues into the 1860s. Some Confederate soldiers speculated that it was Yankee conspiracy, supplying bad powder to Mexico for them to sell to the Confederates.