Dealing with Firearms
Firearms are subject to federal, state, and local regulations, so you need to be careful in how you handle them. In general, however, an executor can usually distribute a typical firearm to any close relative of the decedent, as long as the recipient is not legally prohibited from possessing it.
Certain weapons are regulated by the National Firearms Act (NFA), including fully automatic weapons, short-barreled rifles and shotguns, and silencers. These weapons and accessories must be registered with the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF), and any distributions or sales must be done according to ATF rules.
A few jurisdictions (such as NY and WDC) require registration for more common types of weapons, although an executor usually has a short period in which to possess and then distribute a firearm without registering the gun himself or herself (in NY, this is 15 days). You should check local rules.
Generally speaking, you cannot give a weapon to a person who is legally prohibited from possessing it, such as someone has been sentenced to more than a year in jail, dishonorably discharged from the armed forces, or judged mentally defective (see ATF Prohibitions for a more complete federal list, and note that some states impose additional restrictions, such as restrictions for minors). However, some states, such as NJ (see N.J.S. 2C:58-3j do allow prohibited heirs to take possession of a gun for up to 180 days so they can lawfully sell or otherwise dispose of it.
Note that some states require the recipient of a firearm to obtain and possess a firearm license, to register the firearm, and/or to take a gun safety course.
If selling a gun, a number of states require that private individuals perform a background check on a prospective buyer (usually through an FFL dealer), including CA, CO, CT, DE, DC, IL, MA, MD, NJ, NM, NV, NY, OR, PR, RI, VA, and VT. In fact CA, DE, DC, and OR require the sale itself to be done via an FFL dealer.
Perhaps the legally safest way to transfer or sell a firearm is via a gun dealer with a Federal Firearms License (FFL), who can help you fill out any required forms, hold the gun for you, perform any background checks, and then release the gun into the possession of the recipient when everything is complete (find a local FFL dealer).
See also Gun Laws by State.