If I had to hazard a guess, I would say that 1) cans function better on rifles than on pistols, 2) firearm function is literally very important when committing a dangerous act. So probably criminals would try cans early on on pistols, and realize that they put their criminal lives in a bit more danger, and then they would stop. Also, they would have to be willing to get threaded pistols to do it in the first place.An interesting question to me (and the most important) - If cans became OTC, what would happen to the rate of crimes committed with a firearm?
We are arguing basic mathematics when there is much more involved.
So probably you'd see a minor increase in overall crimes committed with firearms, and what you would see would be more typical rifle crime where a can might be helpful, like poaching crimes and doing stupid shit like shooting car tires to flatten them. But as far as violent crime with guns you would see a small spike then not overall change.
But that is just a guess.