The toughest part of getting a sound glue joint in cracks is getting enough glue in there to coat the internal surfaces thoroughly. Sometimes cracks are just too narrow, or too jagged inside, to push the glue in with even the finest magnet-wire (and I've tried some that's human-hair sized, scavenged from various broken electronics around the house). You can try injecting the glue with a small syringe or forcing it in with compressed air as has been mentioned, and that often works, but you're never completely sure how much glue really went in there.
You said that the crack doesn't run to an edge but does any part of it run through (to the inside of the barrel chanel or into the ramrod hole?). If so, a trick I use on even the tiniest through-cracks is to position the cracked piece with the crack facing up, lay a generous bead of glue well-covering the crack, and then hold the running shop-vac hose over the crack on the back side. This method will pull all of the glue you pooled over the crack through to the other side and it completely fills the crack with glue (when you clamp you can tell by how much glue squeezes out). Really works well. I've even drilled tiny (1/16") holes on the back side of some pieces where the back doesn't show just to use this method. Titebond III is a good choice for this method, thinner than yellow glues and a longer open-time for good clamping opportunity.
Not sure if this will be possible for your situation but it works great when you can use it.
John