The .700 Nitro Express ( made in the 1980 's and 1990 's ) and the new brass manufacturers made even more powerful elephant guns such as the .585 Nyati by Ross Seyfried , .577 Tyrannosaur by Colonel Art Alphin and .585 Gehringer by Karl Gehringer to be made by wildcatters . The late 1980s and 1990s produced the .700 Nitro Express and the new brass manufacturers allowed even more powerful elephant guns such as the .585 Nyati by Ross Seyfried , .577 Tyrannosaur by Colonel Art Alphin and .585 Gehringer by Karl Gehringer to be made by wildcatters .