Dobk,
Colonel John W. Birge's 14th Missouri Infantry had several companies equipped with German Dimmick rifles as sharpshooters. They fought with these 28 December 1861 against Colonel Caleb Dorsey's Rebel recruiting command at Mt. Zion Church near Hallsville, north Boone County, MO and beat back the southerners. Is this the weapon to which you refer?
Bruce Nichols