Since the OP's inquiry was about competition rifles, this might be of interest. Mike Bryant is one of the premier builders of high end competition and hunting rifles. You can scroll down to the 'Stock' section to get his take on things:

https://bryantcustom.com/what-makes-for-peak-rifle-accuracy/

I just finished rehabbing this gun for use as a back-up to my primary Benchrest VFS rig. Initially, the barrel showed .015-.018 of movement when the front action screw was cracked loose. After addressing the bedding and doing new pillars, it now shows right at .001 movement. Recoil lug is bedded tight to the back. The sides, front and bottom have .020 clearance. Barrelled action will literally fall out of the stock when the screws are removed.

Tight:
[Linked Image from i.imgur.com]

Loosened:
[Linked Image from i.imgur.com]


[Linked Image from i.imgur.com]

Since I was squaring up the bottom and sides of the stock, I added this piece of carbon into the bottom of the fore end:

[Linked Image from i.imgur.com]


Forbidden Zoner