{Removing the barrel and sending it back to the factory for reloading IS NOT A TEETHING PROBLEM.}
It is if the process is difficult, since it will eventually be easy. How many gas stations were there when automobiles first hit the road?
“Hell ‘n tarnation, we’re outa gas and there ain’t another gas pump for nigh on two hundred miles. Why’d I ever give up my horse?”
Things get better. We used to crank engines to start them, now we just speak a word.
{That's exactly how the system was designed. It can't be reloaded by the owner.}
Who would want to reload million-bullet barrels? I would gladly let the factory robot do it, thanks. In the same way I take the jet to the airport mechanic for a service, and to the fuel hanger for refuelling. Do I want to refuel her myself, at home, from 44 gallon drums of jet fuel and a hand pump? No thanks. Many things go somewhere to be serviced, refilled or tuned. Inconvenient? That’s life. It will be easier with time, since greater demand creates added drop-off points, deliveries, cheaper costs, etc. Empty chambers will be picked up and dropped off as easily as beer kegs are, behind every hotel, every day. Not a drama.
{Now I'm going to ask you again. Would you but a gun that after shooting had to be send back to the factory just so you could use it again?}
Sure, along with my car for a service, my computer for repairs, my gas cylinders for refilling, my jet for refueling, my robots for de-bugging and my bonsai collection for trimming.
There are no million-bullet barrels. There aren't even 30 bullet barrels. The 1,000,000 rounds per minute is a rate of fire, not an amount of fire. A typical Metal Storm bank holds in the tens of rounds, but can go into the low hundreds, utilizing a boat-load of barrels.