We already have a well known historical example to show that alcohol prohibition is not effective, is veritably unenforceable, and causes a noticeable increase in violent crime due to black market forces.
Why would prohibition on firearms be different?
One is a consumable good and the other is a durable one, which obviously affects how often consumers buy the product. This affects the model of demand, as consumers will repeatedly buy one and only buy the other in a limited fashion. Additionally, one is easy to make, requires common materials, and only a little know how (to the point that people can make it at home without too much effort, if they are so inclined, which many were during prohibition) while the other requires specialized manufacturing equipment, materials, and knowledge to produce. These factors make one far more lucrative than the other, and as such you'd see a far bigger black market for alcohol than guns. These are the same reasons we the war on drugs is an utter failure and yet we are mostly able to enforce the ban on automatic weapons.
All of this goes out the window because you've not accounted for the fact that we already have more firearms than people in the country, and most of these firearms can last well over 100 years if properly maintained.
Also, it sounds like Star Trek, but 3D printing is going to make the creation of some durable goods, even guns, much easier.
Doesn't change the fact that alcohol is much easier to manufacture than firearms. Also, 3D printed guns are quite primitive in their current state of development, and I wouldn't dismiss the idea of some governments passing 3D printing restrictions in the future.
