View Full Version : Locking Shoulders?
11-28-2006, 01:47 PM
I am new to the FAL building. What is the locking shoulder and how does it relate to the headspacing? After my AK is finished, the FAL is next. I have a receiver already (well Wednesday I will).
11-28-2006, 06:51 PM
The locking shoulder is the little pin with a flat spot on it and the kidney shaped head. It presses into the receiver and the back of the bolt is cammed down in front of it when it is locked up. The flat spot is what the bolt pushes against when it is fired, so the thickness of it at that point determines how tight or loose the headspace is. They come in various sizes and the proper size one is calculated and installed during the build. You might want to go over to the FALFiles website and see if GunPlumbers build manual is still available. All the FAL build info you will need in one place, IIRC he also has a video out as well.
11-28-2006, 10:19 PM
What the Kernel said...
The locking shoulder sets the headspace. Buy a pin guage or rent one from someone at the FALfiles. After you install the barrel, remove the extrator ( I have that tool, I'll loan it to you) put in the HS gauge and use the pin gauge to find out size Locking Shoulder you'll need.
If you have one that's too larger you can file down the flat side to fit.
11-29-2006, 11:07 PM
You might want to go over to the FALFiles website and see if GunPlumbers build manual is still available.
GunPlumber's manual and video is available, and he just released it on DVD, so easier to use than the old VHS.