When inletting a barrel, lock, etc, how do you know you're getting close to the bottom of the inlet?
I use inletting black, very dry, on an old toothbrush. You can't really see the film it applies, so it's not very messy. Maple is a dream, because it's so white, the least little bit of black shows up.
I know I'm getting close to the bottom of the inlet, but how close? I certainly don't want to take too much out from under the tang.
So roll up a little ball of silly putty, modeling clay, or old chewing gum, and lay it in the bottom of the channel. It's in the channel, near the breech, about 3/32 in diam.
Set barrel in place, as far as it will go. I use a soft mallet, then really set it with a piece of endgrain maple and a hammer, and also set the barrel against the breech, by endgrain and hammer at the muzzle.
Oh, baby, look how flat the little ball of clay is! I can see the tang needs just a touch of wood removed, oblique flats in the channel can be scraped a bit, and I'm there!