This model was approved on May 20, 1873.  At that time, also approved were the proceedings of an Ordnance Board which selected caliber .45 as the standard caliber for all small arms.  The Model 1873 differs from the Model 1870 primarily in the reduction of caliber to .45, taking a center-fire cartridge of 70 grains of powder and a 405 grain bullet, the cartridge being known as 45-70-405.   The total length is 51 7/8 in..  The barrel length is 32 1/2 in..  The rifling consists of 3 grooves .005 in. deep, with 1 turn in 22 in..  The muzzle velocity was 1350 fps.  Penetration in white pine was as follows: 20.8 in. at 10 yds., 17.2 in. at 100 yds., 12.4 in. at 200 yds., 10.2 in. at 300 yds., 8.8 in. at 500 yds., 6.4 in. at 700 yds., 3.7 in. at 1200 yds. 

      Our specimen is marked on the lock plate in front of the lock “U.S.” “SPRINGFIELD” in two lines and an eagle.  On the front of the breech tang is the serial number 46503.  The top of the breech block is marked “MODEL” “1873” eagle “U.S.”.  The barrel near the breechblock is marked “V” “P” eagle head.  The “V” and “P” appear to be double struck.  The bands are marked “U”.  The top of the butt plate is marked “US”.  There is an inspector’s cartouche on the left side of the stock marked “SWP 1888”.    The bayonet is marked “US”.  The scabbard is marked “WATERVLIET ARSENAL” “J. BOYD”.  The sling is stamped “ROCK ISLAND” “ARSENAL” “E.H.S.”.  The serial number dates manufacture of the breechblock and receiver to the second quarter of 1875.  The inspector’s cartouche dates the stock.  The trigger is the smooth-faced type used before March, 1883.  The ramrod is pre-August 1878.  The lock plate is post-1878.  Prior to this the lock plate was marked with the model year.  The thumb piece is post-March, 1876.  The hammer has the later style checkering and the post-January, 1880 lip under the head.  The sight is the third form Model 1879 sight. The notch in the lower edge of the buckhorn is rounded and beveled.  The fourth form was made straight at the bottom.

The manufacture of 10,000 Rice-Chillingworth trowel bayonets was approved by the secretary of war on March 7, 1873.  They were issued to troops for trial under field conditions.  It was to be held in the hand when it was used to dig a trench.  The rifle was not to be used as a shovel handle.  It was worn in a belt scabbard and was to be fixed to the rifle only in combat situations.  The trowel bayonet was not adopted by the Ordnance Department.

Our specimen is marked on the handle "PAT. APR. 16~72".