Anywere from 200-2000 USD
on the smith and Wesson m4, it means military police, because its sold under thesmith and Wesson M&P line of guns
No
Try e-gunparts.com
I would start my search at Smith and Wesson first.
Yes
No
Yes
You take it to a gunmsith.
@ 1982.
@ 4"
Age of smith Wesson serial no 5K4166