I recently acquired a very nice Spanish M1916 that had been damaged trying to drill and TAPE the WOODEN front hand guard. Rest of the stock was also very smelly and had shown signs of mold.
Disassembled the rifle (metal parts were very nice), cleaned the stock with oven cleaner, let it dry a couple of days, gave it a soft grinding with 0000 steel wool and oiled multiple times with boiled linseed oil.
Ordered a piece of walnut wood from eBay (2$) and took a very deep breath.
It was time to take out the broken wood around the drilled hole with a jigsaw. Never done that before. Took around 20 minutes and 4 saw blades, but came out really nice.
Then took measures from the new cut relief and milled that out of the walnut wood part using a Dremel. Key was to look for a nice piece of grain to fit the missing part in the handguard.
A little bit of filing and the repair block was glued in place using PVA glue. Some larger cracks were filled using PVA glue mixed with sawdust.
Let it dry over night and very carefully filed the repair block into shape. Before reaching the handguard, I switched to 200 grain sand paper. After the shape was fine and I couldn't feel the difference with my fingers anymore, I sanded it further down with 400 grain sand paper.
Gave it multiple coats in boiled linseed oil and reassembled the gun.
Looks awesome and didn't cost 20$ including the new jigsaw. Took around 2-3 hobby nights in my cellar and a lot of courage!
Don't be afraid, it's a very feasible and a MASSIVE upgrade to the rifle.