The 50 Gallagher Carbine was designed by Mahlon J. Gallagher and granted a patented for his design in 1860 and was produced by the Richardson & Overman Company of Philadelphia. The Gallagher was a breech loading rifle and used a lever action mechanism to open the breech, with the lever forming the trigger guard as well. When opened, the barrel tilted downwards to open. This meant that the rifle did not have a fore-end and also no swivels nor had the ability to add a bayonet. The biggest drawback of the Gallagher rifle was the fact that it did not have an extractor/ejector mechanism and spent cases had to be extracted manually or with a knife, a difficult feat when on horseback as well as slowing the rate of fire significantly, made the rifle unpopular with troops.
Springfield Armory Museum – Collection Record