I've used the wateriest cyanoacrylate glue I could get for this a number of times--no need to spread the crack at all, just apply to the crack at the head of the stock and it will wick in. Do not use tape around the sides of the crack, as it will wick under the tape and glue the tape down, requiring mucho cleanup--wax or something you could easily wipe/scrape off would be a better idea.