The "el cheapo" Acra-Glas is still one of the best bedding compounds there is. It was designed specifically for firearms and is easy to work with... especially if you ever want to remove it or alter it someday.
Here is an article on glass bedding from Benchrest Central.
The point of glass bedding is to improve the fit of the barreled action in the stock, so that it is exact, yet does not bind. This involves putting in a layer of gunk between action and stock, with the gun then setting up into a perfect casting that fits every nook and cranny. This can be done with many different substances, but at present the popular way to go is to use two-part epoxy mixes, usually with some filler for srength. The filler can be most anything, but the popular choices are glass fibers (hence, glass bedding), or particles of aluminum or steel. The gunk can be dyed to make it less obvious.
When you do this, you get to (have to) make a choice about what parts of the barrel action you want to have touching the stock. At present, many would agree that these points ought to touch:
--the back of the recoil lug
--the bottom of the receiver, at least around the stock screws fore and aft, plus as much of the rest of the bedding surface of the
receiver as you judge best.
--possibly the first inch or two of the barrel
There are some places that ought not to make contact:
--the bolt handle in its cutout
--any part of the trigger mechanism
--any part that would "over-determine" the location of the action. Thus, the back of the recoil lug makes full contact, but the front, sides and bottom do not. This is to avoid binding.
--the sides of the action screws, whose holes (whether in pilars or not) need to be relieved
--no part of the barrel (there'll be flames on this one, if anyone but you reads this far; everyone's got a gun that shot better with the barrel touching somewhere, but no one ever shoots a gun in BR competition that is set up this way, which is good enough for me)
In applying the stuff, here are some rules:
--strip the action of all the little parts you can
--plug up or tape over any nooks and crannies you don't want to fill up with bedding material
--file, route, scrape, chisel, whatever, the stock material until there is room for your gunk
--apply, then reapply, release agent to any part of the barreled action that might get epoxy stuck on it; ensure good coverage. A good release agent is car wax.
--tape off the parts of the stock that might get hit with excess epoxy
--devise some way to keep the action centered and at the depth you want in the stock. I use wrappings of tape around the barrel to establish the position of the barrel in the forend, and the stock screws to line up the action (I drill out the holes for the stock screws later). An elegant job will minimize these clearances. I tend to favor form over function and leave a good gap between barrel and stock--an eighth or even a quarter of an inch doesn't look bad to me and ensures that your free floated barrel doesn't run aground.
--apply gunk to both action and stock--you'll get fewer voids that way
--use a slow-setting gunk that can be warmed a bit before setting the action in without beginning to set up; it flows better that way and spreads evenly. Of course, you don't want it to run away, so there is a compromise here.
--secure the action in the stock without stress. I just leave the action screws in for alignment and hold things together with not very strong rubber bands. The point is not to build in distortion with your bedding job.
--clean up excess gunk before it sets fully--its a lot easier that way
--have faith--if you did all this right, it will come apart after you let the gunk cure! If not, a heat gun is good.
--these epoxies shrink as they cure. To get a perfect fit, a second coat may be needed. Degrease and rough up the surface of
the first coat to ensure adhesion.
