Vais muzzle brakes have eight small holes drilled from the muzzle of the brake. These holes are drilled through all of the cross ports and terminate in a small expansion chamber just ahead of the barrel muzzle. This configuration very effectively vents most of the noise and concussion away from the shooter. When it comes to efficiency, Vias muzzle brakes are very efficient at recoil reduction as well. Exact percentages for recoil reduction can not be listed for each caliber as it varies depending on bullet weight, barrel length, weight of the rifle and in some cases even the powder used.
Recoil reduction of up to 50% is common with the large 7mm and 300 magnums. On rifles such as the 270 and 30-06 recoil reduction of 40% is common. The reason for the difference is the magnums have a much larger muzzle blast and more energy for the brake to work with to reduce recoil. Big bore rifles such as the 375 and 458 are harder to tame down for two reasons. The heavier bullets produce more recoil and the larger bores burn the powder faster. This leaves less muzzle blast for the brake to reduce recoil. Average reduction for these calibers is 30% to 35%.
Vais muzzle brakes require the work of a gunsmith for threading and fitting purposes.