Something always sinister about our germainian friends and their basements !
Re muzzle break it can serve three purposes
As already stated it reduces recoil by dirverting gas rearward and as it obeys newton's laws offsets the recoil by applying a forward pressure
Secondarily if diverted appropriatley it reduces elevation due to recoil and puts the gun back on original target ( or more closer) for a second shot if needed
I also understand ( although memory fades )!it can also give be used to reduce losses due to the resistance of air ahead of the round but obviously cannot increase pressure to increase range.. Something to with aperture size and location ( front whole is limiting and side vents have a bigger effect in releasing the pressure ahead of the shell and as they do for energising gases from the charge).. I am sure some one here can elaborated... It's all very complicated and nurse called nap time halfway through the explanation