Apologies to UECHI for getting off topic.

Thx for response, Ken, but I'm still confused due to my ignorance of sight changes and the reasons for them.  Per your question, my sight base is an M1898, but the range bar, slider and rear sight w/peep are clearly m1902.  But why?  It seems the most critical component of the sight is not the sight itself but the profile of the sight base ramp since that is tied directly to trajectories and velocities.  Intuitively it would make more sense to modify the sight to the M1902 base while retaining the M1898 rear sight, tangent, etc., unless the flip up peep was only availableon the M1902.  Tx again.

Ignorant and confused in NJ

John