Quote Originally Posted by WeaselFire View Post
Gunpowder still exists, it's what's in the cartridge most people now use in their firearms. Black powder would be what you'd be using in that time period and The Black Hills would be swarming with prospectors as well as some indians.

There are three parts to a rifle shot, the projectile, the powder and a way to light the powder. In modern ammuniiton, there is also the casing that holds all of these together. In your era, there would be the bullet, sometimes a ball and sometimes more of a bullet shape, the powder and a percussion cap or a spark from a flint. Assuming you're not looking for a flintlock, which would still be in use, your most likely choice would be a cap, which sits over a pin with a hole through it to the rifle's chamber. When the trigger is pulled, the hammer falls and strikes the cap. The cap makes a spark which travels through the hole to the chamber, where the powder is located. There is a projectile, or bullet, in front of the powder and, when the powder burns, it creates an expansion of gas that pushes the bullet through and out of the barrel.

Okay, on to the sulfur. The biggest reason for sulfur as a component in black powder (gunpowder) is to speed up the burning process. Gunpowder is basically charcoal, potassium nitrate and sulfur. It's the charcoal that is the main burning component and power, the potassium nitrate just acts as an oxidizer so it will burn. Sulfur provides the smell of fired gunpowder and it smells like, well, sulfur. Think rotten egg.

So your magic could increase the burning rate or decrease it, both could be catastrophic. Too fast and the gun might explode, too slow and the bullet never exits the barrel. You'll need to figure out what you need for your story, which you should really have known before deciding to magically alter the sulfur. Nobody mixed their own gunpowder, it's a fairly dangerous operation, even today. That means they can't just adjust the amount of sulfur to account for your magic.

Start researching guns of the Old West if you need a lot of detail.

Re: the bolded bit. Er...no. Rotten eggs smell is H2S which is a reduction product of sulfur. What is happening here is oxidation, so you will get sulfates, maybe SO2 and a bit of SO3 but definitely not H2S.