As a hobbyist (not professing to be a gunsmith) I've bedded a few rifles. I have had problems with the non-use of action screws or guide screws. The action screws necessarily have to go through the bottom metal, which has to fit into the stock inletting. If you just plop the barreled action into the stock/bedding, how to do ensure the actions screws will line up perfectly with the holes in the action? I had one rifle that I just plopped into the bedding and put some big rubber bands to hold everything together until it set. There was definately a problem with getting the screws into the threaded holes. Things were mis-aligned. Now consider round bottomed actions like the M700 - how do you know things aren't rotated? To me, by having the bottom metal in place and using the actual action screws you create a jig/template that ensures things are in alignment.
