I think it's an '03, just a hint of the accursed Battle Sight looming there; and I don't see a receiver sight.
Why accursed, well I think this guy said it best:
The OPEN SIGHT and the HUMAN EYE A COMMENTARY UPON THE OPTICS OF MARKSMANSHIP THAT EXPLAINS WHY THE OPEN "BATTLE SIGHT" ON THE SPRINGFIELD RIFLE WAS CAST INTO THE LIMBO OF GREAT MISTAKES
By T. Richard Paganelli, M.D.
National Service Military Journal April 1918
Vol. 3 No. 2 Pg. 105
https://hdl.handle.net/2027/hvd.32044090080847?urlappend=%3Bseq=125
It's a pretty good read.