Question for "rocket scientists, fluid Engrs. and other very smart shooters

[Cool Tool]

I personally don't like the style brake you are talking about but if you backbore a brake an leave the exit hole like it is you will get less carbon blow back in your bore an the muzzle is a hole lot easier to keep clean.

 

[SheepDog]

Muzzle brakes work in two ways. First and most important (the seat of the pants) change is you remove the mass of the powder from the recoil engine. The fact that it goes sideways or up or backwards makes no difference to this part of the equation. The recoil reduction is about 33%. A 100 grain bullet and 50 grains of powder. Change the direction of the powder gases 90 degrees and it doesn't add to the recoil. If the powder exits up then there is a bit of down force on the muzzle. I if you change the direction of the powder gases 180 degrees then there is a slight jet action that pulls the gun against the recoil.

Those are the facts but the degree of effect that the direction of the exit gases has on recoil is mostly hype. We are talking about a reaction engine where the thrust is determined by the velocity of the ejecta and the direction it takes. Velocity is directly related to heat and pressure. By the time the gases get to the end of the barrel there is very little heat left and the pressure is somewhere near 5-10000 psi. Your gun begins to recoil the instant the bullet starts moving down the barrel, so for the time that it is in your barrel it is 100% of the weight of the bullet and 1/3 of the weight of the powder causing recoil. Once the bullet leaves the barrel it leaves the recoil equation. The gases accelerate at the moment its expansion is no longer contained by the bullet. If it is ported at that moment or the moment before it will exit the equation before the bullet does. Because only part of the gases are moving in the barrel it doesn't add a lot to recoil until the bullet exits. Getting rid of those gases stops them from contributing to the recoil to any large degree. The larger the port the more gas leaves before it can get to the muzzle. Directing those ports backwards has very little effect on recoil because the thrust equation is mass of the ejecta times (1/2 velocity) divided by the mass of the vehicle. The velocity of the gases coming from the ports is less than the velocity of the bullet because you have changed its direction. So the thrust available to pull the gun IF you could change the direction of the gases 180 degrees (you can't) would be roughly the mass of the powder in K-grams times 1/2 the velocity in meters per second divided by the mass of the gun in K-grams.If the angle is more than 90 degrees the thrust you get is derived multiplying thrust times the SIN of the angle from 90 degrees back. if the angle is 100 degrees from the muzzle then 100-90 = 10. Sin(10) times the thrust is the forward force.

You can calculate it and with sensitive instruments it could even be measure but even the most sensitive person is unlikely to be able to feel the difference. You will notice the bulk of the recoil loss by removing the gases from the recoil but beyond that it is more likely an emotional response to an idea.