We originally set out to design the oil vial in the shape of the .223/ Nato .556 but quickly realized that the diameter of the neck would be too narrow for the oil to pass through freely. This was a deal breaker because really wanted the bullet to be able to unscrew as a cap. We feel this is one of the things that makes it so cool.

The .556 ultimately ended up being the perfect shape because it had wide enough neck and was only slightly longer than a standard oil vial. Some people joke around that the .556 is a commie round and it's Un-American obviously this was not intended. The AK-47 is simply a platform that we were familiar with because it's fun to shoot.