There are many ways of doing things, and this was/is a common one. European gunsmiths would often cap the bolt ends with walnut plugs, aligning the wood grain.
HVA used to install brass threaded pins from factory
As for the imbedded or "hidden" bolt technique, one doesn't need a large bolt, usually less than 1/8" is enough, expecially if some epoxy coumpound is injected into the crack -a small hole can be drilled following the wood grain and the compound injected by a syringe. A variant of the above technique is to drill two crossed holes at an angle (when possible) and insert two epoxyed threaded pins, which are crossing one ove the other through the crack.