What kind of rifle is this?

I found a rifle in my grandpas house, he has several that many of my family dont know about but I do. It looks like a military rifle or hunting. It is 5'5 to 6 feet long. it is chrome, the scope looks custom made. It doesnt use a magazine clip, bolt action, the stock is full metal, and the barrel is thin but not very, so it is neither a small nor big caliber shell like a 30-6 or 50 cal. the muzzel has holes going around it. ( where the bullet exits ) and the holes look like they are for reduce fire from the primer igniting the bullet. My granpa has been in the Vietnam war in the navy but he has done alot of bear hunting in his old days and the fact that he owns a ranch. My question is for the experts, what kind of rifle do you think this is and could you possibly give me a link to show me, along with your own experience. This rifle is magnificent