A gun can be legal in a state, region or a jurisdiction and illegal in another zone. It is impossible to make a list available in the US because there are contrasting guidelines. A gun legally registered in NY can be illegal in Arizona. The gun, even it is unloaded, is considered illegal immediately after crosses the borders of the other state.
Laws are different in some states
The gun is the same, nothing changes, only the laws of Arizona are different. A legitimate purchase in a state can become illegal in another state. Firearms are often exchanged through a transaction between a seller and a buyer. You need to make sure that all ar 15’s have proper cases. Forty percent of firearms transaction take place outside a retail market. In 1994 a law was federally instituted, named the Brady Laws. It is about a background checks on all transactions. After a while this law becomes ineffective.
Gun shows are all over the US, guns transactions never require background checks. The transactions are considered “private” between seller and buyer. The buyer bargain the gun price with the seller.
Their sales are considered legal and perpetuate firearms transactions in an illegal manner. Anyone can purchase a gun through a private transaction without any background check or permit. If an individual leaves a gun show with a firearm, he has an illegal gun. Federal law states that firearms cannot be sold to drug addicts, ex-convicts, minors, fugitive or mentally unstable individuals.
Sometimes, illegal firearms are sold ignoring the state laws, some arms are taking a dangerous form. The sellers can make alterations that do not conform to state and federal laws.
The changes include the gun appearance, scrapping the serial numbers to make the firearm impossible to trace, and fire rate. Sniper rifles, high powered assault rifles can be sold in the US using loopholes with important alterations for each firearm.
A rate of 86 percent of guns used in crime in NYC come from the outside the state. “Junk guns” come from foreign countries and are often used by young people.
Only one percent of firearms dealers are responsible for 60% of gun weapons recovered by the police and traced later.
Firearms traffic at gun shows or flea markets where there are no background checks account almost 26000 guns /year. Almost all guns recovered in crime are used after the first purchase. Almost 30% of crime guns had been purchased in the past 2 years.