Editing Gunpowder (section)

=== Sulfur-free powders ===
[[File:Burst muzzle loader barrel.jpg|thumb|upright=1.25|Burst barrel of a muzzle loader pistol replica, which was loaded with nitrocellulose powder instead of black powder and could not withstand the higher pressures of the modern propellant]]

The development of smokeless powders, such as [[cordite]], in the late 19th century created the need for a spark-sensitive [[blasting cap|priming charge]], such as gunpowder. However, the sulfur content of traditional gunpowders caused [[corrosion]] problems with Cordite Mk I and this led to the introduction of a range of sulfur-free gunpowders, of varying grain sizes.{{sfn|Cocroft|2000}} They typically contain 70.5% of saltpeter and 29.5% of charcoal.{{sfn|Cocroft|2000}} Like black powder, they were produced in different grain sizes. In the United Kingdom, the finest grain was known as ''sulfur-free mealed powder'' (''SMP''). Coarser grains were numbered as sulfur-free gunpowder (SFG n): 'SFG 12', 'SFG 20', 'SFG 40' and 'SFG 90', for example where the number represents the smallest BSS sieve mesh size, which retained no grains.

Sulfur's main role in gunpowder is to decrease the ignition temperature. A sample reaction for sulfur-free gunpowder would be:
:<chem>6 KNO3 + C7H4O -> 3 K2CO3 + 4 CO2 + 2 H2O + 3 N2</chem>