Although the Model 300 was never produced in great numbers, it served as a test bed for the development of a new class of long range sniper ammunition. The Model 300 was originally designed for a new 8.58x71mm cartridge, which would later be refined into the famous .338 Lapua.
The Model 300 is a bolt action precision rifle. It is equipped with a detachable box magazine holding 4 rounds of 8.58x71mm ammunition. The heavy barrel is free floated and fluted. The stock is fully adjustable and removable, along with the pistol grip. The rifle is not equipped with open sights; instead a scope is attached with a quick-release mechanism.