Part of the design.
You can request an owner's manual for free at the S&W web site.
1961/62
100-400
You can get a manual for free by going to S&W's web site.
http://stevespages.com/pdf/s&w_pistol.pdf to download a manual
Introduced Jan 1990.
The ammunition that it is chambered for.
100-500 USD
Best left to a gunsmith.
The 3914 was made in 9mm
Best left to a gunsmith