Wood glue works on dry non oily/sappy woods. Most surplus rifle stocks have too much oil/cosmo in them, heck some seep out oil in the sun or when they get hot from shooting. Hence, then best glues that work are listed above. If you want a wood glue that can be inserted into a crack and may or may not hold together then Titebond III or Purbond polyurethane works a little better on oily woods. Purebond foams up and the crack must be clamped together securely so it does not open and dry showing a glue line/crack. If securely clamped and it holds/bonds ok, then most of the times the crack is hard to see after the glue drys.
So on dry woods like hunting rifle stocks any wood glue water based or polyurethane would work. Purebond is used in boat building.
I find best results using acetone to clean the wood then use epoxy glues for a sure fix bond. Hence, most used Decon 2 ton or best: Brownells Arcaglass .
For dry woods normal glue is fine and most hunting rifles never had the cosmo problem or motor oil as a way to keep the stock dry and condition a stock.
Wood pins produce more bonding surface and if the crack is oil soaked it allows for the best clean wood surface surrounding the crack so glue holds the crack, but mainly the additional area allows for the best bond and a stronger repair. One can also use a number of vertical wood thin bamboo pins to pin the crack together. The tiny hole is fixed/filled with a wood dust/glue mix made from the drill dust and your glue. This sort of homemade putty will match the surrounding wood. Others let the wood pins or wood patches over cracks show as seen in the original Russian wood repair link. Use hard wood dowels or bamboo pins. I have also used fishing rod fiberglass pins cut from the thin sections of fishing poles. These will have to be given a rough, uneven surface so more glue holds the pins. I do this to both wood pins and fiberglass dowels/pins. Never use tooth picks. You can also use brass pins set in like nails with some glue. But they can come loose. Some use screw-like, brass pins that are both glued and screwed into/across the crack then set even with the wood or lower and the wood dust putty is used to patch/blend in the small hole to hid its location. Generally, my pins are never larger than pencil lead. It all depends on the pins position, type of crack, location of the crack, and type of repair called for. Do I want it too show or be hidden? Most pins are done inside the stock so the metal action hides the repair.
So I never just glue a crack; I reenforce it so the glue in the crack has a stronger back up. You also have to find the reason why the crack occurred. What caused the problem? Find out and also fix it .
For dry wood like furniture, clocks, wood toys, or cabinet repair where dowel pins came loose from moisture and the old hide glue, then Titebond III Ultimate works great. It is a water clean up, polyurethane wood glue that does not foam up or creep so much. It is a inexpensive great wood glue for non oily or really sappy wood. So I guess you use what you like- my experience on surplus stocks taught me use Brownells ACRAGLAS ($25 a kit) or Devcon 2 ton epoxy ($4-$6)
depending on the amount of repair needed. If the glue fails it is almost impossible to clean the failed poorly sticking glue from a tight crack and get it tight so it looks hidden with the correct glue on the second try. The crack is sort of forced open by the older failed glue and it produces a wider glue joint/crack that just can not clamp together without leaving a visible glue line. You also have produced a poor bonding surface for the correct glue on the second attempt. With a tight crack that you have opened slightly and are forcing glue into with a syringe, you generally have one try to glue it and clamp it for a real tight repair fit. You generally have one shot at getting the glue in and holding on a tight crack. I want the job done the first time and pay a little extra for the better glue on oily wood. Granted they have a short shelf life- I generally use fresh glue each time. Wood glues can sit for a long time and still work fine, epoxy mixes not so much. Always check the date on the glue you use, you do not want a one two year old epoxy kit. The type of wood is a factor in what glue to use. The type of repair is also a factor in the choice of glue. If it is two broken pieces that can be separated, then the surfaces can be recleaned and reglued more easily. Some real craftsmen like Candyman or Cabinetman repair splintered breaks where I would just get a replacement stock. Can you guess what glue they use?
Granted Candyman is the forum wood expert and I have not heard from him in awhile, maybe he will comment. It is always best to read his many stickies- he is an expert at wood repairs and finishes.
This is a great post that remains intact without photo loss http://m14forum.com/stock/84336-how-mak ... stock.html
I will add even with an epoxy you can have a glue job failure under stress-- That's why the repair is backed up by pins, dowels, or wood patchs.