I like to glass bed my guns. I'm not looking for pro's or Con's on that topic. I've made up my mind years ago about the benefits of Acraglas. I take a lot of precautions to ensure that it'll come apart tomorrow. Acraglas is awesome. But accidentally glue the barrel in the channel, and it's in there forever.
The barrel that I have already has the dovetails cut in for the tennons, the touch hole is drilled, as is the bolt hole in the tang. All of those are tightly packed with clay before a very generous coating of release agent is sprayed on the barrel. I make a small "dam" at the end of the stock with clay. This keeps the glass in the channel and not running onto my floor. I spray the INSIDE of the muzzle and then place a ball of tape inside it also. I used 25 ml of glas at the 1:4 ratio. I've found that 25 ml is about right for a 42" barrel. I then tinted it with the same stain I will be using for the stock itself. I level the stock and then spread the glas mixture through the channel using a popsicle stick. I make sure that all of the wood has a light coating before the barrel is dropped into the channel.
Set the barrel in the stock and clamp it in place. The clamps aren't farmer tight. They're finger tight to make sure that everything stays where you put it. But, not tight enough to squeeze out the liquid.
Immediately wipe the excess off of the stock if any comes out. A rag slightly damp with some vinegar works the best for that purpose. (Glacial Acetic Acid is even better).
I'll leave it clamped until tomorrow morning and then pull it apart.