I've done 3 cheapo factory synth stocks (proly a 30% glass filled polyester type of material).
Dexter Hysol Epoxy Patch (aluminum filled) or JB weld.
Can use tubes in hollow to lessen epoxy amount needed. Used stainless tubes for 1st one, proly try carbon arrow shafting if I do another and want to lessen weight.
Free floated all three, bedded recoil lug on 1st one. No action bedding. Did that with Microbed on a walnut 700 way back. Worked great. Too much work (refinished stock as well).
Plastic is better for my uses.
Sporters in .243win doing half inch at 100. Good enough for me.
