Some of that inaccuracy was the fault of the owners. A new owner would swap out the wooden stock for something really cool looking and not realize the screws on the gas block could only be tightened to 14 INCH pounds. Not Foot pounds. The barrel would get sqeezed and goodby simply bad accuracy to something truly horrible.
Never checked that. It was a “stock” stock, but didn’t check the screws.
Sold it for a wedding ring, and then bought an AR!~