Originally Posted by poleok
I was told by one of the best barrel makers that most of the time the problem is the factory DIDN'T square the face of the action and when the barrel was screwed down tight it tweaks the chamber. A good smith can fix it, then you will have a great shooter.)
Poleok's right. Heard the same thing from a few top barrel makers and the 'smiths who chambered 'em and screwed 'em into faced receivers for rifles that set records more than a few times.
The problem's a high point on the receiver face. Barrels typically have a shoulder on their tenon that's quite square with the chamber/bore axis. But that high point on the receiver face bears hardest against the barrel when its torqued in. As the barrel heats, it expands and extra stress at that high tends to change the way the barrel whips when the bullet's going down the barrel. Pulling the barrel, facing the receiver square with its barrel tenon thread axis is easy, then put a spacer on the barrel tenon equal to the thickness of the metal faced off the receiver, touque in the barrel, it's sight holes now clock in perfectly and heat's no longer a problem. Seen this done on many hunting rifles. that turned them into thinble guns instead of bucket guns (makes tiny groups instead of huge ones). Properly squared receiver faces is about 90% of what makes one shoot great or otherwise.
Then ther's barrels that werent' heat treated properly and when they heat up, the stress lines uneven tension inside bend it just enough to shoot noticably bad.
Ruger built 20 M77 rifles with custom single-shot actions and the front screw vertical into the receiver ring's flat for the US Palma Team in 1991. They contracted Green Mountain Barrels to make the steel pipes they called barrels. Ruger didn't know what a Palma rifle barrel had to be like or accuracy levels expected. Nor did Ruger ask anybody what rifling specs were best for Seirra's then new Palma bullet. 10 of them (those with 6-groove rifling) were bucket guns. 9 of the 4-groove barreled ones were 'cup' guns; they shot only half as bad as the bucket ones. Only one rifle was semi decent, but not as good as the guy's rifle it replaced as his own broke just before the 1992 World Palma Matches started. Everyone else on the 16-person team shot their own rifles. With the poor trigger, stock design and accuracy those Rugers had, they kept it pretty quiet.