The person who can obtain and is legally permitted to have such weapons is probably going to be a dealer. This type of dealer will also probably have considerable pull with the local government and law enforcement agencies.
I would expect a firearms dealer to have a considerable cache of weapons both in their homes and place of business. Therefore, I would expect such a person to utilize automatic weaponry to protect the cache. Lets say I had a cache of weaponry in my household or place of business. Would it be reasonable for me to have available just a pistol to protect said weaponry? Considering the stories about armed robberies and gang activity nowadays, I would be surprised if the firearms dealer did not have an automatic assault rifle at the ready to defend the weapons cache.