I took some thin walled brass tubing (and in one case aluminum) and slide/glue over hardware store SS long bolts. You can buy thin-walled tubing at hobby stores that cater to RC Plane builders. I'm lucky because our hardware has a big selection, so I can usually find the right thread. If not, cut off the threaded part and re-thread as needed.
Point being you want smooth walled straight shank slippery surfaces that will allow the bedding to set with the action aligned as it will be when installed. The thin-walled tube bolt cover gives a slight clearance for the future real action screws. Or, you can use good tape to make the clearance cover. But most tape does not come out as well as metal... In one case I used a plastic straw from DQ to slip over the action screws.
That's why Brownell's sells the T handle long screws. They are shiny and with wax or PJ they don't bond. They extend up through the stock enough so you can pour in your epoxy compound while the barrel and action are "up", and then push down into the bedding while it sets. I just make my own long ones from local materials ...
I do not use the screws/bolts to do any clamping. They are just a guide. I use surgical tubing or saran wrap and small bungee cords to hold it all together while it cures. Surgical tubing will usually come free of epoxy on its own. Bungee's will not without the Saran wrap.
You do not want any pressure points that you might get from using screw-down torque. The bedding is the "uniform" pad that develops after cure. Once it's hard (may take days to fully cure), the action and chamber area are uniformly supported w/o pressure points. The barrel generally free floats in it's channel without touching anything.
For wood stocks that may swell or change shape a bit with weather, I have been painting in a coat of CPES (Clear Penetrating Epoxy System) which is now available at many builders supplies. It's been used in the marine trades for decades.
You can tape up your stock and just leave the barrel channel exposed. Paint in the CPES until the wood will not take any more. Wait a few minutes and wipe it up with a rag. The wood will be stable and will not absorb water/moisture form that location any more.
Actually, since I'm usually doing a full refinish if I'm this far into the wood, I use aniline dye over bare wood which sets in about an hour, then CPES all over. When it's just tacky to the touch, I put on a coat of Min-Wax Polyurethane satin varnish which bonds to CPES like crazy (tacky/wet). Other brands of poly do not work as well.
The first bonded coat of poly will be followed up later with 5 or 6 more coats in satin for my final finish. It is my home version of the factory hard stock finishes, and it's pretty tough.
So that's bare wood, stain, CPES soaked in, Min-Wax Poly on the outside. Bedding epoxy under the action/chamber over CPES if you want. A coat of CPES in barrel channel and sling mount holes.
Let it sit for a week after popping the action then carefully sand and start the exterior finish. Somewhere in there, I reset the action to test and look for edges where I need to be careful with the Poly varnish. Sometimes a little file work so the bedding will release the action relatively easily when you want to clean/lube. It takes a week or two to do all this one coat at a time with 24 hour cures, sanding and re-coating.
