The Sten was a blowback-operated submachine gun firing from an open bolt with a fixed firing pin on the face of the bolt. This means the bolt remains to the rear when the weapon is cocked, and on pulling the trigger the bolt flies forward under spring pressure, stripping the round from the magazine, chambering it and firing the weapon all in the same movement.
However, the current day semi auto version of the Sten has a different operating system, and does use a movable firing pin.
Find a good gunsmith or machinist
A firing pin that is mounted on/in a hammer
Firing Pin Block
Like it says, the firing pin rotates as the action cycles.
What should Firing pin protrusion measure?
By action of the hammer striking the firing pin, forcing it into the primer.
Firing pin is what strikes the back end of bullet igniting propellant
You can find a firing pin for the ranger at Numerick Gun Parts Corporation.
Try e-gunparts.com
How to replace a firing pin from a Charles Daly 20-gauge semi automatic
I am looking for a firing pin for a Crescent Firearm I believe the serial # is 8894
Firing Pin