Originally Posted by pmh-usa
Running into same problem with an MPI stock blank that I'm building up for a Mod 70 (coincidence, not a M70 issue). AFTER I made sure that I had relieved enough to re-float the barrel by hogging out the forearm, this is what I did:
I got some small aluminum "H" channel - cut a "trench" with a dremel in the bottom of the forearm all the way from the recoil lug trench forward to within and inch of the for end . Made it really rough and jagged, just made sure that the aluminum would be below the 'flush' line. Mixed up fiberglass resin, with some added chopped fiberglass filler to thicken slightly, and poured it in - once it was set up (fiberglass is very hard and stiff), I carefully applied 5 layers of 10mil tape to the barrel and finished glass-bedding the forearm. When that was set up, removed the action, peeled the tape off and now my forearm was rigid and free-floated.
Note: if you still have a few touch points, buy some 3/4, 7/8, and 1 inch dowel - staple some 60 grit sandpaper to pieces of dowel and use to sand down the high points - if in doubt use 6 or 7 layers of tape.
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This will work fine and is very similar to how I've done several stocks, both Rem and Winchester plastic factory stocks.
In the channel you can use the H metal, angle, or even cut pieces of brass or steel (stainless is my favorite) in the trench.
I epoxy mine in place with Devcon and if you want to add some additional weight to the fore end you can mix some lead shot, or steel filings (easy to come by at your neighborhood welding shop that has a chop saw set up) which not only adds weight but even more rigidity.
I'm in fact in the process of doing this with an M70 Extreme Weather H-S precision laminate with an aluminum bedding block.
To add the weight it's best to make that center channel wide and deep, just be careful not to eat a hole all the way through.
I will do this stiffening and weight adding first and then follow up in a second phase bedding it full length using a similar spacing method. I just use one thickness of Gorilla Tape (Gorilla duct tape) along the bottom of the barrel and once I've filled my bedding channel with the Devcon I lay one thin sheet of Saran Wrap or similar plastic wrap over the channel before dropping in the barreled action.
I've been able doing this to make some really cheap wobbly stocks into something you can have confidence in.
On these cheap plastic stocks I will also rout out from the lug back to the rear of the space inlet for the action along the bottom and edges enough of a channel to insert a piece of 1/8" steel rod (all thread works out fantastic) and epoxy it in place which will really add a lot of rigidity through that critical area as well.