Colt New Model Revolving Rifle

the Colt New Model Revolving Rifle was made by the Colt Manufacturing Co. in 1855 based on the Colt Model 1855 side hammer pocket revolver by Elisha K. Root, it was used during Pony Express and the U.S. Army during the Civil War but was highly disliked by soldiers due to a flaw of the gun called "cook off" which was when smoke from the bullet going off couldn't leave the cylinder resulting in a burst off hot smoke hitting the user, due to Cook Off the gun became less used and ultimately discontinued in 1863.https://en.wikipedia.org/wiki/Colt%27s_New_Model_Revolving_rifle