I remember they had a hunting regulation back the early 80’s that only allowed 5 rounds in your rifle for deer/elk. My dad had an M1-Garand, which was legal in Washington, but he drew an Oregon out of state tag, so he had to borrow my brothers 7mm.
There are 5 rd ‘clips’ for the Garand. I’ve hunted States that have a 3 rd max, maybe that’s what your Dad got up against.