To fill the fore-end, I applied a two step process, using two different epoxy resins.

The first step was to fill the voids with liquid epoxy resin, the second step was to bed the barrel with an epoxy paste.

The first epoxy resin - ONYX Slow Epoxy Resin is applied in liquid form. This makes it simple to completely fill all the voids in the fore-end. This resin is already black, so it does not need tinting. You have to finish the application within 5 minutes of mixing - it sets quickly.

The same material can be used to fill the butt of the stock, as it will flow into and completely fill any shape cavity.

The second epoxy resin is a paste - Epidermix 372. This is used in the second and final stage of bedding the barrel to the fore-end. The entire contents of two 90 ml containers is enough to bed a bull-barrel, after the bottom of the fore-end is filled with ONYX resin.

If you would like to add a bit of weight to the rifle, or balance it out, you can mix the required weight of lead shot into the ONYX resin before pouring into either the butt or the fore-end.