Tachunter,
When you do it, the best method in my experience is to bed it all at once; receiver, lug, and entire barrel channel. It is never as accurate if you bed the receiver and lug area, then do the barrel. The cold joint, even when bonded well, causes accuracy issues.
Might seem a bit intimidating at first, but take your time preparing everything, mix up more bedding compound than you think you will need, and don't let it rush you once you start. I always start applying the bedding in the middle of the barrel channel and work both directions from there. Make sure you have the sides of the channel thoroughly coated all the way to the top of the stock first, and then down into the bottom.
I use a tongue depressor to sort of squeegee the bedding along the sides and up to the top. From there, it's simply a standard bedding job, with the receiver and lug area compound flowing into the barrel channel.
Now, take a good look at everything, relax, and begin to set the barrelled action into the stock. I always set the receiver tang into the stock first, and let the rest of the metal sort of fall down into the compound under its own weight. It will settle in and begin to squeeze the compound out from under the metal. Apply enough pressure to set the metal into the stock to the proper depth.
Okay, almost there......remove the excess bedding compound with anything that will not scratch the metal, and put it back into the mixing container, then into the freezer. You can use it later for small jobs, or to skim bed the rifle you are working on.
Don't let this job frighten you at all, and whatever you do, don't rush! It is done no differently than an ordinary bedding job, just more area involved, and takes about three minutes longer to do. Even if it takes you fifteen minutes longer, you will be fine. The compound will take much longer than that to start hardening, once it is spread out in the stock.
Ted