For those not inclined to educate themselves on gun laws, here is a listing of federally mandated punishment for using a firearm in a crime.
Federal Penalties for Using a Firearm in a Violent Crime | Law Offices Of Robert David Malove
There are state laws that mirror the federal laws concerning the use of a gun in a crime. There are all kinds of consequences for using a gun during a crime. It is a federal crime for a convicted felon to possess, own or use a firearm. Problem is that prosecutors will often accept a plea deal dropping these charges in order to get a quick conviction to clear the court docket. A law not enforced is less useful than no law.
Many guns are obtained by prohibited individuals through a "straw purchaser". Too often prosecutors do not prosecute these people. There are all kinds of laws that were passed in the belief that it would deter criminals from possessing guns. Laws don't prevent crime, they just provide the means to prosecute a violator.
What it all boils down to is criminals don't obey laws, only honest people obey laws, and laws not enforced are no deterrent.