some high production firearms (such as the pps-43, mp-40, and the zastava m70b) make use of metal stocks in order to have a strong, thin stock that can be folded away in order to make the weapon more compact. even a skeletal steel stock is often heavier than the equivalent wooden fixed stock. consequentially, less cost-sensitive designs like the fn minimi make use of aluminium or lighter-than-steel alloys. a few designs, like the accuracy international arctic warfare, use a metal chassis which securely beds the components of the firearm, with non-structural synthetic panels attached for ergonomics.