Way back in Part I, I cut down the wood stock and removed most of the material from the SPS Mounting Plate. With the foundation of the upgraded stock set, I started working on the recoil buffing and length adjustment mechanisms.
I started by sanding the SPS mounting plate to within ~1/16 of an inch of the profile of the wood stock. This was tedious work as I'm trying to not mess up the finish on the wood itself.
Below you can see the recoil reducing springs and adjustment mechanism attached to the butt plate. The springs are ones I picked up at the local hardware store, that fit around the SPS's guide rods and had what felt like the right amount of give for recoil reduction.
My selection of these springs was not particularly scientific. One thing I wanted was them to be under pressure no matter the position the stock is adjusted to. That's why the extend beyond the end of the guide rods in the image.
The adjustment mechanism is a set of 18-8 stainless steel door hardware from McMaster Carr. The binding barrel will be inside the wood stock, but will catch against the back of the SPS's base plate. The barrel is long enough however, to stick through the SPS's base plate so that I can hold it in place while tightening the screw and shorting the length of pull.
Sorry if that doesn't make sense, the images will make it more clear.... keep reading/scrolling.
I removed the SPS's base plate from the stock to drill the large center whole which will allow the binding barrel nut from the adjustment mechanism to move in an out as the butt plate absorbs recoil.
Then, I counter sunk the butt plate so the screw end of the adjustment mechanism would sit flush.
With the length of pull adjustment ready to go, it was now time to cut and sanding the over-sized butt plate into shape. Measure, mark, cut, sand.....
Here's the main stock components after the rough cuts of the butt plate were done. I'm using a simple hex nut on the adjustment screw to hold the butt plate and mounting plate tightly together as I begin sanding the profiles.
Here she is sanded down into the rough profile and attached to the stock in the shortest length of pull position. I'll keep it in this position while I sand the aluminum components down to make the stock's profile.
Finally, a couple pictures of the stock sanded to final shape with a random orbital sander and extended a bit further. These parts are now ready for final sanding and paint.