Gosh golly gee...My wife and I get 2" at 100 yards with milsurp, and about 1.5" to 1" at 100 yards with modern commercial. Now we just shoot at the 300 yard gong at our range with open sights. Our 13 year old daughter is starting to do the same.
Methinks a lot of the accuracy issues with these rifles is the person pulling the trigger... It's a long creepy trigger, and one has to learn by experience and practice as where it lets off. Also it's fun for pointing out who in your shooting group has developed a flinch.
As for the rifle, can they be tweaked?
Yes, to start with work on the barrel harmonics, if it has a bayonet fold it out as the point of impact with the iron sights were set to this configuration.
Remove any barrel/bayonet lug attached bi pods, and don't use them.
If you have a receiver cover scope mount...put it in the recycling bin, and go back to the original set up or attach a proper side mount scope.
Add a buttpad that will allow for a proper length of pull...unless of course your build is that of someone from Asia, or you wear a Vintage Russian battle coat to the range.
Use better ammo.
And finally practice, practice, practice.