Both the Amphibia S as well as the Sporting .22 sound great! But, they should be silent to zombies as well, but they're not. I was on a night server in a city, and killed a zombie with the Amphibia, and zombies from all around came running towards me. If you kill a zombie with axe, other zombies don't care, but shooting both Amphibia and Sporting causes agro from all zombies within a 200-300mtr radius.