nitro express elephant guns were first made around 1895. they used smokeless powder, which was new at the time. with smaller metal-cased bullets with sizes from .400 to .620 and speeds around , they had a much better trajectory and penetration over the black powder guns. in a few years the big bore guns disappeared from the gamefields. early 20th century rifles came out in single shot, bolt action, and double rifle ways and were used until ivory hunting died off in the mid 20th century. then the guns switched roles to tools for game wardens and as backup firearms for professional hunters guiding international hunters.