To clarify, I did not elbow my gear. I ran full tilt sprint at the other team airsofting, and misjudged the distance to a metal structural pole on the field. My regulator knob sideswiped the the pole and the brass fitting holding the knob to the regulator broke off. While that happened, the air tank snapped back into my right elbow (since I wear my tank in a satchel under my right arm).

Both the tank and I survived contact just fine, and the entire assembly has since been repaired as above.