Need some help on a hatchet i'm putting a new handle on. The old handle had a crack that started where the blade guard had a rivet went through the old handle.

New vs old, I've thinned it down a bit before fitting the hatchet to it, but I'm struggling with how to remake the "trench" for the guard. I also wanted the new handle to be slightly longer, as I'd like to avoid having the trench terminate at the end of the handle, weakening the wood further.

This old handle was cut from a cracked 22" handle from a Michigan axe I got from my grandpa, I figured I would save what I could from it. Thinking of thinning down the swell a bit, but not too much.

So the real question, does anyone have any experience carving one of these before? I've thought of drilling some holes and doing it with a chisel, or using my miter saw to carve most of the trench out first before resorting to a chisel. The difficulty will be in stopping the saw from making trench from going through the swell, as I've measured it out so that the bottom of the blade guard will be just above it. This hatchet is a wedding present for my older brother, and I'd like to incorporate the guard in, but let me know if someone with little experience shouldn't ruin the handle by trying!

New vs old, I've thinned it down a bit before fitting the hatchet to it, but I'm struggling with how to remake the "trench" for the guard. I also wanted the new handle to be slightly longer, as I'd like to avoid having the trench terminate at the end of the handle, weakening the wood further.

This old handle was cut from a cracked 22" handle from a Michigan axe I got from my grandpa, I figured I would save what I could from it. Thinking of thinning down the swell a bit, but not too much.

So the real question, does anyone have any experience carving one of these before? I've thought of drilling some holes and doing it with a chisel, or using my miter saw to carve most of the trench out first before resorting to a chisel. The difficulty will be in stopping the saw from making trench from going through the swell, as I've measured it out so that the bottom of the blade guard will be just above it. This hatchet is a wedding present for my older brother, and I'd like to incorporate the guard in, but let me know if someone with little experience shouldn't ruin the handle by trying!