Best glue to repair this stock?

Get some quality CA (super glue). I've used Zap-A-Gap (hobby/craft stores) for many stock fixes similar to that and cracks. Another good CA glue is Hot Stuff from hobby shops. Wick it under the edges and apply pressure. If you try and lift it for thick glues you may crack it off and get a splintery edge.. jmo

Regular yellow glue will work fine for that repair... I don't always use it, but it's probably what I would use for that.

Use a straw to blow it deep into the crack...

DM

You can buy hypodermic needle type applicators to inject the glue where you need it.

I have a stockpile of West System epoxy I would use in this instance as it takes a long time to set up and you could position the stock let it run in whichever direction was logical.

CA should work fun as long as you can quickly and decisively clamp it.

Another idea:
https://www.brownells.com/gunsmith-...icks/wood-finish-repair-sticks-prod12618.aspx

If your working on a wood stock you can color the glue with sawdust from a similar donor wood or if it is dark like walnut you can rub a charcoal briquet on sandpaper to make black dust to mix in with your glue.

I would use CA as previously stated. Simple and easy fix.

Whatever you do, make sure you dye the glue darker than the wood or even black. Wood grain naturally appears darker than wood and those lines will blend better with wood grain than the wood itself. I’m still kicking myself after I got supposed “stainable” wood glue to use on an irreplaceable stock and the stain didn’t take at all. Now I have white lines through the wrist of a 140 year old milsurp.

Surgical tubing is nice on stock repairs, can tighten it down and tie it off to keep the joint tight, but not compress the wood. May not be an issue here given where the repair is but food for thought.

Bellow I would explain how I would deal with that situation:

Accept the fact that you will have to refinish the whole stock in order to achieve a good, quality repair. If you are satisfied with sloppy work, one that's just for repairing that stock to function without care for the looks, you might skip the bellow text.

You have a big piece with several cracks here, so a CA glue might not be the best solution as you will not have the time to properly apply it to all of the surfaces and press the piece to blend in with the stock. You simply risk to leave a raised piece that is not completely glued - small patches of glue here and there. Instead use a good quality waterproof wood glue, but NOT the fast curing one - I'm quite satisfied with Bison brand wood glues, but they might be tough to find in the US. Lift gently the cracked piece with a thin blade and insert generous amounts of glue with a syringe. After you're done press hard on the piece several times with your fingers so to squeeze out all the excess glue. Clean all of the excess glue with a wet rag, thoroughly - don't worry that the edges will not be covered with glue, you want that and you will deal with that later. This is actually why I use wood glue - I can easily remove all of it from the surface so I can fill the cracks properly later.

Put the stock in a machinist vise, level it, cover the piece with some thin nylon foil (old grocery bag, food wrap foil...) and put weights on top to press the piece leveled with the stock. Surgical tubing might not be the best solution, as the cracked piece is on a flat surface and the tubing can't apply sufficient force to press it down. Leave it to cure for 24 hours. Sand the stock and proceed to fill the cracks with your finishing media of choice. You may use shellac - apply small amounts of it into the cracks and sand it gently with 600 grit sandpaper with a backing. Repeat until the cracks are all filled and blended with the surface. Instead of shellac you may use TruOil - in that case leave it to cure until it starts to feel tacky and proceed with the sanding. I don't like to use steel wool for that application - it leaves fine steel particles and it will contaminate the seam.

After you are satisfied with the result, apply wood stain (optional) and finish the stock with whatever you like - BLO, TruOil, polyurethane...

Proceed to have fun!

Hide glue. It doesn't leave behind finger prints and glue lines like most other glues do. It drys very rigid and has been time tested for decades. Other glues will creep and leave a distinct glue line ridge on the wood surface.

Avoid wood glue. It’s about the worst food stock repair. Most of the fast drying glues end up too brittle for stock repairs.
Devcon clear 2 ton epoxy with the 30 min set time is very good. It gives you time to work and blends good with wood.
Here’s a repair done with Devcon.




The problem you are going to have is matching the finish. Your stock is made of a light color Birch and the factory finish has the stain mixed with it . Any sanding when cleaning up the repair will leave a little color area that will be almost impossible to match, unless you are good at making your own alcohol base die.