Colonists had little trouble obtaining firearms in the 1700s. Some bought them from Europe, some bought them from local gunsmiths who often used imported parts, some acquired them legally or illegally during wars, and some bought government surplus firearms.
Colonists used black powder to load their firearms. However, black powder was expensive and had to be imported from Europe. Lead for balls and shot was also hard to acquire. This meant colonists had to use powder and lead efficiently.