Harold Vaughn was a bit of an expert on the physics of rifle accuracy, and he wrote about this issue. To summarize, it is surprisingly hard to make a really rigid threaded joint. Just 2-3 threads end up taking all the load.
There is a way to make the barrel-receiver joint rigid, by cutting threads with a special profile.
The symptom of a non-rigid joint is fliers.
If I understand his writings correctly, forestock pressure will only help of the problem is fliers.
If you can't do the special threads, then forestock pressure will pre-load the receiver-barrel joint. Sometimes that works. The lore I've heard says that you want about 8 pounds of upward force on the barrel. Vaughn recommends that this be accomplished with two nylon screws in the forestock, at about 90 degrees. The screws are tightened to provide balanced force and the right amount of force. I've personally never seen that done, but that's what he recommends for those who feel an overwhelming urge to apply forestock force.
And to comment on MD's correct statement that fluting does not increase stiffness: That's right, but it does increase the Q of the barrel. That is undesirable. More Q contributes more barrel whip.
Last edited by denton; 07/30/22.
