In 1816, Springfield Armory produced one variation of the standard length M1812 Type II Flintlock Musket which utilized left over M1795 Springfield locks.
All of these locks are dated 1813 and were altered by grinding off the tit at the rear of the lockplate. It is believed that approximately 250 M1812 Type II muskets with these altered M1795, 1813 dated, locks were produced. All of the existing specimens are dated 1816 on the buttplate tang. In all other respects, these variations of the M1812 Type II, are these same as any other Type II M1812.
See pgs 327 & 328 of
U.S. Military Flintlock Muskets by Peter Schmidt or pg 94 of George Moller's
American Military Shoulder Arms Vol II for more info.
While it is thought that only 250 of this variation were produced, they do show up on the collector market, more than you would think.