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The Union Carbines

The Union Carbines’ breeches, as seen through the patents, evolved from a complicated rolling breech to a more simplistic hinge-like design. The inventors also strove to find the most efficient way to seal the breech and the combustion chamber located at the end of the barrel. The inventions featured a ring-shaped “shoulder” and then cone-shaped “protuberance” used in sealing the breech.The

First Patent
In 1859, Edward Gwyn was granted a British patent and Henry Gross obtained an American patent (number 25, 259) for the same carbine design.1 That design was a model for the breech-loading Cosmopolitans. Gross’ patent focused on the breech. He claimed the rights to the “revolving chamber” that held the cartridges. As the guard lever was pulled down and forward, the chamber shifted back through a series of pins and grooves, allowing the shoulder (see next paragraph) to move out of the end of the barrel. The pins attached to a metal piece, called a “bed,“ that is connected to the chamber.  The chamber moved backwards when the guard lever was being pushed down and forwards when the guard lever was being pushed up. The bed remained stationary so that when the chamber was moved all the way back, the groove on the bed, where a pin (“roller”) was located, aligned with the chamber’s groove, enabling the chamber to shift down.  By rolling the breech down using the pin and groves, the carbine’s chamber was in the ready to load position. The cartridges just slid into the barrel when the breech was open.

And its Patents

The Second Patent

In their 1862 patent, number 36,769, Edward Gwyn and Abner Campbell claimed an invention improving the carbine’s breech. Their breech, used in the Gwyn & Campbell carbine, was much simpler in design than Gross’s. In their patent dated October 21, 1862, Gwyn and Campbell included the rights to the curved guard lever that locks in place by a metal piece attached to the stock of the gun. They also patented a horizontal spring that helped to hold down the back end of the breech plug when the plug was in the loading position. The spring also helped guide the breech plug into the edge of the combustion chamber located at the end of the barrel.  The breech plug pivoted on a “screw-pin” that first moved perpendicularly to the gun until it was over an inner fulcrum. Once at that position, it moved horizontally. These two motions, which form an arc, combined to push the breech-plug’s shoulder into the chamber. They claimed the rights to an iron cam that rested against the breech plug’s shoulder on one end, and “in a closely fitting seat” on the other side of the breech plug to relieve pressure of the weaker parts of the gun. Finally, they patented the concave impression on the top of the breech plug that aids in the insertion of a cartridge.  This patent simplified the breech mechanism and allowed the carbine to be more durable.​

The Third Patent

Henry Gross’s Patent number 39,479 dated August 11, 1863 demonstrated variations in the breech mechanism.  The back of metal plates located on the top of the breech block were attached to the carbine by a pin allowing them to move up and down in a hinge motion as the breech block itself moved vertically. The downward movement of the guard lever forced the cylindrical cam or eccentric to move, sliding the breech block with the shoulder or plug back until it cleared the barrel.  Then the entire breech block, including the above mentioned metal plates, moved in a downward motion, allowing the cartridge to be inserted. By pulling the guard lever up, the action was reversed. The plug sealed the chamber, and the carbine was ready to fire. This patent was a variation of the previous patent for the movement of the breech. More similar to the second patent than the first (with the rolling breech), the third patent’s breech block moved in a horizontal and then vertical motion when opening the breech.

The Fourth Patent

The last patent secured in relation to the Gwyn & Campbell belonged, again, to Henry Gross. In Gross’ 39,646 patent on August 25, 1863, he claimed his invention to be a “conical or curved protuberance,” in which the ring-shaped shoulder was replaced by a rounded tip (the conical protuberance) that sealed the top of the barrel of the gun.  His invention used the breech lever to operate that protuberance, which slid backwards and forwards. He also claimed the rights to a spring-powered lock to latch the guard lever in place.  His patent was only slightly different in many aspects to patent number 36,769; however the major difference was the protuberance described above.

1 Thomas B. Rentschler,  Cosmopolitan and Gwyn & Campbell Carbines in the Civil War: A Definitive Illustrated History of Two Rare and Unusual Civil War Cavalry Carbines and Their Use in the Field (Lincoln: Andrew Mowbray Publishers, 2000), 19 - 20.

2 Arcadi Gluckman, Identifying Old U.S. Muskets, Rifles & Carbines (New York: Bonanza Books, 1965), 337.


When putting up the guard lever, the chamber, pins, and grooves worked the opposite direction to close and seal the breech and barrel. The breech was sealed by the breech block that had a “shoulder,” a rounded metal edge (shaped like a ring) that fits securely into the barrel. When the guard lever was pulled up, making the breech block slide forward against the opening of the barrel, it prevented a gas leak from the joint of the breech and barrel.2

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