People who are in prison due to a harsher penalty, who would otherwise have been back on the street, are in prison, and thus have a bit more trouble committing crimes on the street, on account of being in prison.
“Ah, what about overcrowding?”
End prohibition. Parole/pardon non-violent offenders. Besides giving us the room in prison for the criminals who actually should be kept separate from the rest of society, it could also be expected to make the lifestyle of a drug dealer less glamorous as the cash flow underpinning the violent criminal enterprise can be expected to dry up.
But you already knew all that from the first two times I’ve answered this question from you. Third time’s a charm, or can I expect you to ask this again?
Actually, it would make it harder for law-abiding citizens to get guns in the first place. The impact on the gun supply of criminals is a knock-on effect.
In theory the initial spike in violent crime should dwindle as the guns work their way off the black-market by one way or another. In practice, the effects of international smuggling, theft of government/LEO weapons, and possibly illegal gun-smithing would contribute to the criminal gun supply.
Regular folks would remain disarmed.