Depending on where you are, a local gun shop may be able to run a stolen gun request for you. You can do that in Tennessee, *IF* your local gun shop is willing to do it. Otherwise, you will probably have to check with the local Police Department.
Gun Broker, Guns America, Guns International
Zip guns are considered homemade guns. Do a Google search on Zip guns to find out how.
Library, gun show, gun shop, on line
Gun shops, guns shows, want ads, machine gun forums.
You will have to call to find out.
Blue Book of Gun Values
there is a gun iny pants loL
Gun shops, gun shows, estate sales, on line auctions
Provided you are not a convicted felon, you can buy long guns at 18 and hand guns at 21.
A great place to look for guns for sale is on www.gunbroker.com, there are also many store in areas that sell guns, If you find the gun on gunbroker, you will have to buy the gun through a FFL liceanse holder
45 caliber Machine Gun and 50 caliber machine gun
Most guns actually have their maker on the gun itself. Check the side of the gun.