The Metcalfe device was invented by Ordnance Department officer Henry Metcalfe and patented in 1875. The blocks were to be issued pre-loaded and carried on the belt. Only 100 Model 1870 and 1,008 Model 1873 rifles were fitted with the devices. The Model 1873 examples appear to have never been issued and are assumed to have been nearly entirely disposed of via disassembly or sales. The rifle also has the other standard Model 1873 markings and features, including an "ESA" cartouche. The serial number falls in early 1876. The included block contains seven deactivated .45-70 cartridges.

Fair as modified and fitted with a Metcalfe device. It has mostly an artificial smooth plum brown, 30% original dark case colors on the lock, oxidation concentrate on the buttplate, general minor marks and scratches, and smooth gray and brown patina on the balance. The sanded refinished stock has some minor chips and dents throughout and minor repairs around the device. Mechanically fine.

Standard markings and features. The stock is stamped with a boxed "SWP/1893" inspection cartouche. With "U.S." marked spike bayonet with blue steel sheath and leather hanger.

Fine. 80% original blue and casehardened finishes remain with small scratches and nicks throughout, minor edge wear, crisp markings, and areas of a thin brown patina. The stock is also fine with scattered dings and bruises, and crisp cartouche. Mechanically excellent. The bayonet has been reblued.