I decided to build up the comb to give me a good cheek weld. I thought about a kydex riser, but just don't like how they look.
To make the syntactic foam I used West System 105 resin with 207 hardener--I used the 207 because I also plan on using this to clear coat the painted stock. I mixed this at about a two thirds epoxy to one third microballoons by weight, this was about 60% microballoons by volume. Basically, after adding 14.0 g of microballoons to 42.8 g of mixed epoxy I then kept adding microballoons until it was the consistency of sticky bread dough.
The first batch I mixed was slightly too small and I tried to do a 50/50 mix by weight. This is way to many microballoons and before I added them all in I had to stop as it was the consistency of playdough and no longer sticky.
Having mixed more than was needed, I decided to use it all and sand it down later. The saran wrap let me work it into shape pretty easily and I found it needed some needing to work epoxy out of the mix and onto the stock.
After sanding. It should be noted that it was much easier to sand with four days of curing than with two. Even so, it is still harder than sanding pine wood.
Today I just added a layer of fiberglass. While the syntactic foam is tough, and the fiberglass is overkill from a durability perspective, it covers several air bubbles in the syntactic foam that would have needed to be filled before painting. That, and I have always been a fan overbuilt.
Total weight added to the stock by the syntactic foam after sanding was 23.9 g (so I sanded off 27 g). Of course I will update with the weight added by the fiberglass layer once it is finished.
I like the Bat Machine action screws. The salt bath nitride finish on top of a stainless steel screw is nice and unlikely to corrode. However, what I really like about them is how deep the hex is cut.
The Bat Machine screws have a lower profile head than the Kimber screws and sit below the surface, especially the rear screw (pictured above). This does not bother me, and I even like it. However, I can see how it might bother someone else.