[RandyP]

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.

Rifles
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.
AVB-7.62
AVS-36
Dragunov sniper rifle (including Chinese NDM-86 variant)
JS 7.62
SVT-38 and SVT-40
PSL sniper rifle
M91
Berkut-2M1
IZH-18MH
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.