Elizur Bates was first employed there at Springfield as blacksmith and forger starting in 1816... making pieces, parts, barrel bands, finishing, assembling weapons... and he was also making/forging bayonets... Bates was the Master Armorer there from 1834-37, then resigned from that role but continued to work there in other capacities, and later served as an inspector for there and he stated he traveled to the other armories "inspecting newly made arms and stamping".
There are other similar period bayonets that have US/SM, and US/TA and assorted others stamped in exact same fashion and lettering style.... One would generally assume this most likely the inspectors marks.... However did not find any known/listed inspectors there or at other armories with those specific initials, so could be assumed these may actually be the forger's mark instead.... or possibly could be either/or... Just an observation...