From Forgotten Weapons. I was wrong 200 were made
There is big debate as to its use in the Civil War, which seems silly to me. The gun was produced to a number of 200 hundred and all existing (18) are stamped with British proof stamp for Confederacy. While existing orders for the actual guns have not been found, there is a receipt from the Confederate Richmond Arsenal for the ammunition used by the LeMat carbine, suggesting that they may have been used. And truly, if put yourself in the builders' and Confederates' situation the gun was built (no question) and the Confederates would certainly have taken whatever was available. The documentation suggests that the Confederate government rejected the carbines on the basis of price, but a small number may well have been acquired by individuals or small units.