I have a 742 in 30/06 that shoots 1 1/2" at 100 yds with rem core lokt 150 and 165 gr. My dads mid 80's 7400 shoots about the same. Try different ammo and check the sights. I have 2 hunting buddies that have 742's with consecutive serial numbers. Both their guns will print under 1" at 100yds.
The last time I had a gun that shot 12" groups the barrel was loose. Some auto loaders have a nut that holds the barrel tight to the action. I have never checked my 742 but that nut was loose on my 22 auto. Hold the butt stock and the barrel, wiggle, if its loose you should feel it move.
You can't fix stupid....however ignorance can be cured through education!