It is a single-action revolver with a high capacity nine shot cylinder. This weapon's high capacity allows for more shots between reloads and allows the player to gain the upper hand, especially in short, intense firefights. In singleplayer, this weapon is capable of killing an enemy with one shot to the chest or head, and is capable of taking down some predatory animals with one shot as well, such as wolves if aimed properly at the head.
The real life LeMat was a cap and ball percussion revolver, but in the game it is depicted as a break-top revolver using traditional cartridge ammunition. While cartridge conversions of the LeMat were made, they did not see production until long after the game is set.
In reality, the original LeMat featured a 16-gauge smoothbore barrel beneath the main barrel that could fire a single charge of birdshot or buckshot. While this second barrel is modeled visually on the weapon in Red Dead Redemption, it is unusable.
Right after reloading, the hammer is left in the uncocked position until the first shot is fired. After this, the hammer becomes cocked and will be cocked back for the remainder of the rounds in the cylinder or until the next reload. This odd occurrence affects all firearms with a visible hammer in single and multiplayer.
After the mission An Appointed Time, if the player gets into a shootout with the Mexican army, the Gunsmith in Escalera will run away and never return, leaving the LeMat unable to be purchased (It is possible to undo this glitch by camping in the wilderness for about five days. The gunsmiths and store merchants should respawn then).