I have done this several times. I cut the stock to length I want. I then cut a piece of Poplar, usually from a skid and sand down until just nearly fits into stock. I then fill hollow part with expanding foam and let it raise up and cure overnight. I then finish fitting the poplar piece untill it will just barely start to go. Then with a hacksaw or dremel cutting wheel, make notches every 3/8 of an inch all around the edge. I then degrease the inside of the plastic stock with acetone where the wood will fit, let dry for 10 minutes. I then mix up a generous coating of acraglass bedding compound, add plenty of the glass flock, and coat insideof stock and fill all the gaps, and a generous coat on the edge, and tap in flulsh with the bottom of the stock. Wipe off excess, and let stock sit upright overnight, preferably in a vise. Next day drill holes and screw on your pad. I use poplar because it wont split or splinter out like oak, hickory will, learned that from my neighbor who builds custom cabinets, what he makes mos of his frames out of. Hope this helps, have done them from .223 to 300 win mag, no problems yet.