Pillar bedding and glass bedding make a lower compliance fit between barreled action and stock.
The forward momentum of the projectile and gas causes a rearward reaction in the barreled action.
[Mass of the bullet][velocity of the bullet] + [Mass of the gas] [ 1.5 time velocity of the bullet*] = [Mass of the barreled action] [Velocity of the barreled action] + [% coupling of the barreled action to the stock before bullet escapement] [Mass of the stock] [ Velocity of the stock]
What does all that mean?
If we can get the stock to move with the barreled action before the bullet escapes, then we can count the stock mass in when we calculate how far the gun moves before bullet escapement.
That is why .223s do not shoot any better when bedded. They already have good enough coupling with the low action to stock peak recoil force. AND the barreled action is a larger multiple of the bullet and gas mass.
I like Wagner for pillar bedding Mausers:
Bedding the Front of the Action
I like Russ Hayden for pillar bedding Rem700s:
*I learned from Wagner to wrap the screws in tape in order to center the screws in the pillars.
*I learned from Wagner to score the pillars so that the epoxy would get a better grip.
*It took me a while to figure out that I wanted to score action screw holes in the stock with 7/16-14 tap, after drilling with 13/32".
*It took me a while to figure out that I like Devcon Steel Putty, so I don't have to fight time or gravity.
*It took me a while to figure out that I wanted to make reduced head screws (< 13/32")dedicated for fixturing, so I could pre compress and locate the pillars.
*It took me a while to figure out not to use brass or stainless 3/8" O.D. tubing as pillars, but to use Chrome Moly 3/8" O.D. tubing for pillars. The brass makes dissimilar metals and the stainless is hard to machine on the lathe. You might think Aluminum pillars with ~1/3 the Young's modulus of steel, but ~1/3 the density could be made stiff enough, but it has dissimilar metal problems too.
*It took me a while to figure out that I wanted to wrap the barrel with tape with just the right number of turns to locate that end of the barreled action.
*It took a while for me to figure out that I should assemble the barreled action with the pillars and jack some dummy rounds through it, to make sure I have the correct mate between magazine and receiver.
*It took me a while to learn that rifles with the first inch of the barrel supported with bedding shoot better than those with more or less.
*It took a while to figure out that a good bedding job will have sustain on pure fundamental note it makes when the barrel is struck with a soft object while the rifle is supported at the wrist. If it does not make that sound, chisel out some epoxy and start over. A buzzing sound means interference. A short tone means interference and/or high compliance.
Someone on the internet is talking about synthetic pillars made of G-10, getting the material from McMaster-Carr. It is stronger than steel. I did a calculation on cost to weight saved, and it was way over the $10/ ounce that I nominally pay for rifle weight improvements.
*My father, chief engineer over 150 engineers and draftsmen for 40 years, designed guns with "Hayes Elements of Ordinance" that said to use the 1.5 factor for the powder velocity.