Physics of muzzle brake recoil reduction

[carlsbad]

I'm no muzzle brake expert but I am a physicist. I see some occasional mis-information around and thought I'd address it.

EDIT: The below discussion is meant to discuss the recoil reduction associated with gas jets leaving the muzzle brake. There is recoil reduction associated with stopping the gasses coming out of the muzzle and this recoil reduction occurs in all brakes, no matter how they direct the gases. Hope this makes it clearer.

Forces are easily resolved into independent vectors. Translation: all forces to the side can be ignored when looking at recoil reduction by a muzzle brake. So whatever goes sideways is irrelevant.

The muzzle blast has to be directed rearward to be effective. Now it can be directed rearward and sideways both. That is what normally happens. The shooter feels nothing but the guy shooting beside him gets blasted.

Muzzle brakes that only point sideways direct blast backward too. It reflects off the baffles and comes out sidways and backwards.

Muzzle brakes most effective at directing the blast backward, by laws of physics, are the most effective. So I almost always use a muzzle brake with ports directed toward the rear in favor of the simple sideways ports.

If you want the brake to also resist muzzle lift, one of two features must be incorporated into the design: either holes in the top or the ports on the side must be pointed slightly upward.

Another simple rule is the less blast goes forward through the bore of the brake, the more effective it is at reducing recoil. So having your hole precision bored just over the bullet size will make it more effective. I use .020" over bullet diameter.

Finally, the baffles create a force on the bullet as it goes by due to aerodynamic pressure. So long as the bullet is centered in the hole and the hole is nicely uniform at it's edges, the forces will exactly cancel and there will be no deflection. This is why is is important in my mind to mount your muzzle brake on the barrel with and undersized bore and then bore it exactly coaxial with the bore of the barrel.

--Jerry

Here is the perfect muzzle brake in my opinion. This brake is on a 300 Norma Magnum. It has less kick that my 6xc without a brake.

 

[rbduffer]

Excellent write up! Does your brake correct for barrel torque imparted by the rifling. If so how do you calculate it?

 

[Comrade Terry]

What kind (brand) of brake is that?

 

[carlsbad]

What kind (brand) of brake is that?

muzzlebrakesandmore.com IdahoCTD on the forum. --Jerry

 

[carlsbad]

Excellent write up! Does your brake correct for barrel torque imparted by the rifling. If so how do you calculate it?

Well, i've never thought of that. Do some brakes claim to do so? Could be done with special porting but that's a graduate level course. See line 1 of my original post. --Jerry

 

[carlsbad]

Disclaimer: I am not associated with any muzzle brake manufacturer. I have used and like Nathan's brakes. I have encouraged him to get a shopping cart on his website so people can go there and buy in one step. I think his product will sell itself. --Jerry

 

[msinc]

I aint no physicist, but I am one of those that would a whole lot rather take the recoil than the back blast. it makes me flinch, so I am either going to take the pain from recoil or just shoot a smaller rifle, one of the two. If it comes down to me having to shoot something that needs a rifle so big and powerful that it just cannot be done without the need for a muzzle brake I will find another hobby.
That said, my brother-in-law had a Ruger #1 in 220 Swift. He had one of those J-P Enterprises recoil eliminators installed and we tried it out. The thing looked ridiculous, like something that belongs on the end of a tank or artillery barrel. It lived up to it's name, "recoil eliminator"...I mean there was none, zero. It was strange to shoot the rifle because of the crazy, galactic nuclear back blast yet the rifle did not move.
Now, if there is such an animal that knocks off even half the recoil and all of the back blast I might be down for trying that!!!!

 

[gunnermhr]

If the holes on the side are pointed down, wouldn't that lift the muzzle? You'd be pushing the gas downward, in effect doing just the opposite of drilling holes on the top?

 

[DRNewcomb]

.....
Forces are easily resolved into independent vectors. Translation: all forces to the side can be ignored when looking at recoil reduction by a muzzle brake. So whatever goes sideways is irrelevant.
.....

Except that blast that is redirected to the side does not contribute to backward recoil. The unburned power, gases, flames, etc that comes out of the muzzle contribute to total recoil, not only the bullet. Insofar as these can be redirected to the side, they reduce recoil.

 

[dcali]

A significant portion of the recoil energy comes from the momentum of the propulsion gasses (for example, a 40 grain charge pushing a 150 grain bullet, and the gas goes faster than the bullet). Venting them sideways is absolutely not irrelevant, and is in fact the primary mechanism by which brakes work. And since the line of action of the recoil force is typically higher than the restraint on the rifle (your shoulder), any reduction in recoil will also reduce muzzle rise, no top holes required.

 

[mikecr]

by laws of physics,

What Laws? This implication should always be qualified.
Your standard JP Enterprises brake, a standard used all the way up to tanks, produces no rearward thrust. It uses the momentum of gas hitting sideways diversions like a wall, to pull a gun forward.

 

[carlsbad]

What Laws? This implication should always be qualified.
Your standard JP Enterprises brake, a standard used all the way up to tanks, produces no rearward thrust. It uses the momentum of gas hitting sideways diversions like a wall, to pull a gun forward.

read again. You didn't get it all. I never said the sideways nozzles don't work. They work because they do create a rearward component.

The JP provides more thrust by being huge. You'll get more thrust in a smaller brake using rearward facing outlets. The angled exit ports in the JP also helps direct thrust rearward. --Jerry

 

[carlsbad]

A significant portion of the recoil energy comes from the momentum of the propulsion gasses (for example, a 40 grain charge pushing a 150 grain bullet, and the gas goes faster than the bullet). Venting them sideways is absolutely not irrelevant, and is in fact the primary mechanism by which brakes work. And since the line of action of hte recoil force is typically higher than the restraint on the rifle (your shoulder), any reduction in recoil will also reduce muzzle rise, no top holes required.

The physics here is incorrect. But I'm not an arguer. --Jerry

Except that blast that is redirected to the side does not contribute to backward recoil. The unburned power, gases, flames, etc that comes out of the muzzle contribute to total recoil, not only the bullet. Insofar as these can be redirected to the side, they reduce recoil.

That is a different way of describing the rearward component that the non-rear facing brakes create. They would create more if they were directed backward but this may be enough for you. See my paragraph 4. I never said they didn't create a rearward component. It just isn't in the gases going out sideways. --Jerry

 

[carlsbad]

Ok. Time for a re-statement/clarification. I never said the side facing brakes don't work. They just don't create as much recoil reduction as the rearward facing ones. They work by creating a forward force component handling gases. They just don't as much as the rearward ones. The rearward ones are the most efficient and therefore create the most recoil reduction in the smallest diameters. I wrote my original post carefully.

--Jerry

 

[mikecr]

Ok. Time for a re-statement/clarification. I never said the side facing brakes don't work.

You began the thread with this as your entire basis:

Translation: all forces to the side can be ignored when looking at recoil reduction by a muzzle brake. So whatever goes sideways is irrelevant.

In this, you were/are wrong. And that you can't accept this, drains your credibility.

 

[dcali]

Your original post is still incorrect. Gasses ported exactly to the side will reduce recoil. Conservation of momentum. It's high school physics.

 

[SheepDog]

The most effective brake I have seen had vents that were shaped like an airfoil. The vents were curved to force the gases back at about 60 degrees from the direction of the muzzle. They were only on the side with no top ports but they did a very nice job of reducing the recoil. I don't remember the brand name but it was a remarkable piece of engineering and machining.

 

[DRNewcomb]

The most effective brake I have seen had vents that were shaped like an airfoil. The vents were curved to force the gases back at about 60 degrees from the direction of the muzzle. They were only on the side with no top ports but they did a very nice job of reducing the recoil. I don't remember the brand name but it was a remarkable piece of engineering and machining.

The most effective brake would have the cross section of a turbine blade, which would indeed closely approximate and airfoil. You can look at the brake as either redirecting the gases backward or pushing the muzzle forward; just to ways to view the same thing.

 

[Aero]

I aint no physicist, but I am one of those that would a whole lot rather take the recoil than the back blast. it makes me flinch, so I am either going to take the pain from recoil or just shoot a smaller rifle, one of the two. If it comes down to me having to shoot something that needs a rifle so big and powerful that it just cannot be done without the need for a muzzle brake I will find another hobby.
That said, my brother-in-law had a Ruger #1 in 220 Swift. He had one of those J-P Enterprises recoil eliminators installed and we tried it out. The thing looked ridiculous, like something that belongs on the end of a tank or artillery barrel. It lived up to it's name, "recoil eliminator"...I mean there was none, zero. It was strange to shoot the rifle because of the crazy, galactic nuclear back blast yet the rifle did not move.
Now, if there is such an animal that knocks off even half the recoil and all of the back blast I might be down for trying that!!!!

This animal is called a suppressor. Certainly they don't knock off half the recoil, but they do a really good job of taking care of the back blast.

-Eron

 

[carlsbad]

Your original post is still incorrect. Gasses ported exactly to the side will reduce recoil. Conservation of momentum. It's high school physics.

Nope. Gases that were moving forward and stopped will reduce recoil but there is no rearward component to a gases gases moving sideways. Now a sideways facing hole may port some gases slightly backward depending on how they are handled internally but there is no rearward component to a sideways moving gas which was the whole point of this post.

Another way to look at it is this: If you have a stream of gases of moving forward and you stop them, you will create an acceleration. Lets call it A1. If you direct them backward, you'll create an acceleration, call it A2. A1 and A2 are in the same direction. If you direct them sideways, you'll create a sideways acceleration. If you direct them equally out both sides, that acceleration will cancel. If you direct them sideways and backward at a 45 degree angle with acceleration A3, the the rearward component of the 45 degree blast is A3 cos45 = .707A3.

Cos 90 = 0 so as the direction approaches sideways, (90 degrees) then the rearward component of the acceleration created by the gases is 0.

if you direct the gases exactly sideways, your recoil reduction is limited to A1.

I'm not trying to bash people who like the sideways ported brakes. If you have one you like then by all means I'm for it. I've installed several lately.

In fact, I installed one that directs the gases forward. I might even put one on my AR15.

https://www.gunsamerica.com/blog/kineti-tech-muzzle-break/

I haven't heard back from the guy I installed it for yet but it is supposed to reduce the noise on the line a lot. You still get A1 in the discussion above but A3 now goes against you...I think the geometry works to make A3 quite a bit smaller than A1 so you still get some recoil reduction but you don't really need it with a 223 anyway. His install was on a 6.5 CM so we'll see how he likes it. I also made him a second brake that was more conventional.

--Jerry