War of Mexico-America

I wanna start a topic about a rarely talked issue, mexican-american war of 1846-1848, why do you think mexico rarely won any battles against the american army, no manpower, inferior weaponary, bad tactics???

I read that the mexican soldiers had to use less gunpowder than the americans due to fear that the guns might explode and that made the bullet very weak and short range due to their american c**terparts who had more state of the art rifles also their cannon had the same problem as the guns but the mexican soldiers were still very able to defeat the american army.