Unloading columns can be tedious and we experimented with various methods ranging from an auger and battery operated electric drill, but loved this one the best.
We simply clamped an end cap on one of the column, that was plumbed with a valve and connected to a 125psi tank.
Hee, hee, hee, it was so much fun that everyone present had to fire off at least one blast. Fire in the hole!!!
Be sure to wear eye protection and be considerate of others!
Ready, clear the range!
Fire in the hole!