The .500 Maximum, also known as .500 Linebaugh Maximum and .500 Linebaugh Long, is a revolver

Revolver

A revolver is a repeating firearm that has a cylinder containing multiple chambers and at least one barrel for firing. The first revolver ever made was built by Elisha Collier in 1818. The percussion cap revolver was invented by Samuel Colt in 1836. This weapon became known as the Colt Paterson...

 cartridge developed by John Linebaugh. Only a small number of custom made 5-shot single action revolvers, such as the BMF .500 Maximum manufactured by Gary Reeder Custom Guns, the Ruger Bowen .500 Maximum

Ruger Bowen .500 Maximum

Ruger Bowen .500 Maximum is a 5-shot single action revolver chambered for the .500 Maximum cartridge, based on a Ruger revolver and manufactured by Bowen Classic Arms Corporation....

manufactured by Bowen Classic Arms Corporation and revolvers manufactured by John Linebaugh or Jack Huntington, are being chambered for this round, with a barrel length of up to 6.5" with no muzzle brake or ports.