Are you a 1.12.2 player (modded, surely) who wants to be able to craft gunpowder? Do you not want to have to get extra dimensions or trains (which are, admittedly, quite cool) in order to do so? Or perhaps you simply want sulfur and niter to spawn in more realistic locations, or in a more realistic manner? If that sounds like you, you need Realistic Gunpowder, which does exactly what you desire. Pyrite ore can be found near lava; niter can be found in deserts; charcoal can be crafted into dust; and sulfur, niter, and charcoal can be combined into the powder you normally have to kill creepers to obtain. Plays well with mods like More TNT and MrCrayfish's Gun Mod.
Better textures coming soon! Maybe.