with the peep sights on my 1917 remington i can shoot 2" groups at 100 yards. and thats a completly stock gun thats 80years old using the cheapest ammo we could fine at the gun show ($17 a box of 50). assuming he can shoot thats no problem at all. i dont understand why people think you have to have a scope you shoot small groups.
also there is luck, he may have hit it by luck though i would give him the benefit of the doubt

propmahn
save the world, reload your brass