Uh-oh, then it sounds like the flight went terribly bad for the model to be on the ground when the ejection went off.
Well, if it was on the ground when the ejection fired, then I have one theory on why the bulkhead at the front end of the tube would blow out. The pod has a lot of mass, and the glider has a lot of mass. When the ejection goes off in mid-air, the pod not only gets kicked backwards, but the glider also gets kicked FORWARDS. But if it was already on the ground, the glider was not going to slide forward too easily.
Indeed you have not given much info yet, so possibly it did stick the landing? Perhaps with the nose into the ground, and the aft end angled up a bit. Indeed, for the pod to travel as far thru the air as you describe, that sounds like a mortar firing off at a shallow angle, not a model laying parallel to the ground.
Anyway, if the glider was stuck and unable to get kicked forward at ejection, then the pressure of the ejection charge kicking the pod out the back may have built up a lot more than when the glider can get kicked forward. And that higher than normal pressure may have been enough to blow out the front end of the tube (or bulkhead - I have never built one), even though the pod had achieved enough backward momentum to travel as far as you described.
Or, if that was not it, another cause could be if the pod was not a reasonable slide-fit, or if when it started to eject backwards the chute around the pod might have jammed.
The nose section being blown out reminds me of what happened to my first R/C X-1 model in 1984 or so, on its one and only flight. I wont go into all the details, except to say the engine was supposed to eject and yank about 4 ounces of noseweight out with it. Effectively the ejection charge overpressured the engine compartment, causing the front end of it to blow out, which in turn caused the entire rolled balsa rear fuselage to blow apart.
- George Gassaway