I do not to get to reply first to too many posts. Welcome, this bunch is very informative and helpful. No drama either!
I have no idea why the why of the front sight. Maybe they wanted you to get a bargain.
A photo of the other side of the rear sight will be helpful to the experts.
And I fairly certain your serial number begins with a 3, sometimes the numbers were pressed in to deep.
Butlersrangers beat me. Oh well.