...ton of guns...
...ton of street drugs...
The two cannot be compared without more information.
The guns could be of any type and harm level would vary accordingly. They would too vary depending upon the accuracy of persons firing the said weapons. Additionally, one needs to take into account where the death missiles hit in each body and the physical health of the recipient.
When attempting to decide about drugs; here too, there is no definitive answer. People have different tolerance levels.
I'm not assuming all the guns/ammunition or drugs will be used.
The only assumption is that one ton of each will be available.
Many people own and shoot guns for target practice and defense but never fire them offensively, though some do so to commit violent crimes.
Some people probably try to use recreational drugs without causing harm to themselves or others, financially or otherwise; but they always do because, if nothing else, recreational drugs are a waste of money.
Of course, you could say that guns and ammunition are also a waste of money.
But are there any uses of recreational drugs that aren't harmful? Only if you are the type of person who denies harm because you like them.
Ultimately, I think there's also a case to be made that guns are like a type of recreational drug, like video games; but they do have a defense-function, and deter crime to some degree, so they are actually beneficial in that sense.
Recreational drug use, on the other hand, has no benefits because sobriety is in no way deficient as a state of consciousness.