Re: 7.62x54 hunting ammo
per the Wiki articles, the following are rifles that have been chambered in 7.62x54R - not shown are all the models of machine gun that used the round.
The various Mosin-Nagant bolt-action rifles including the sawn-off "Obrez" pistol.
The American Winchester Model 1895. Approximately 300,000 made for the Russian army in 1915-16.
Dragunov sniper rifle (including Chinese NDM-86 variant)
SVT-38 and SVT-40
PSL sniper rifle
SV-98 (Snaiperskaya Vintovka Model 1998)
Alejandro Sniper Rifle
It is most probable that your dad has one the Mosin-Nagants. There is NOTHING wrong with them either of course, it is plenty accurate enough for most common hunting uses out to a couple hundred yards. My brother can ring the 1000 yard gong most times with his 91/30 with a Scout scope.
Lee Anniversary and Lee Classic 4-Hole Turret, presently reloading .380, 7.62 Nagant (32-20), 9mm and 45ACP