The prone grip on our rifle is different than most other biathlon rifles. A typical stock will have a handstop that slides along a rail. Our stock uses this rail principle, but because of it’s minimalist design, the handstop also needs to include a shelf for your hand. To allow for a large area of adjustment, this shelf needs to be cantilevered. We had to figure out how to keep the grip strong and stable despite a large free-hanging section.
The first step was to create a wooden model of the grip. This took two iterations and countless hours of sanding. From there, we made a silicone mold to reproduce this wooden grip.
To accommodate this cantilevered design, we conducted some experiments. We were pretty sure we wanted to make these grips from a polyurethane foam, but we weren’t confident that would be enough. So we poured one with just the foam, one with fiberglass reinforcement, and one with carbon fiber reinforcement.
Here is the mold with a carbon fiber weave.
After the parts cured, we did some unscientific flex testing. In this application, the foam part benefited the most from the carbon fiber reinforcement.
With that testing complete, we made a small batch of carbon fiber reinforced polyurethane foam grips for use on our preproduction models. After a quick prime and sand, and a textured coating, they’re ready for use.