That one-shell rifle is really useless.
At first minutes when you need something silent vs zombies (that could hear even supressor) - you get the gun that can call whole city to kill you, but, hey, it has one bullet.
Hope it should be lever-action 1887 winchester, or maybe soviet mts255
https://en.wikipedia.org/wiki/MTs255
It can be cutted of
https://topwar.ru/uploads/posts/2018-12/1546041634_oc62.jpg