Recoil?

[Bullet]

I have a 50 Beowulf. When I shoot it my shoulder gets bruised. I say this is from the recoil. I used this term (recoil) because I believe everyone understands what I mean. When does recoil occur? I have read threads about muzzle brakes, springs, buffers, weights. Could someone explain what causes recoil in a Beowulf AR and what is the difference between ways of reducing it? Which are most effective in reducing recoil?

 

[Tony Williams]

If you read the article 'Basic Ballistics' on my website, that has a section describing how recoil is calculated and what factors affect it.

I would expect a muzzle brake would be less effective for a .50 Beowulf than it would be for a high-velocity rifle cartridge, because most of the recoil impulse would come from the heavy bullet and only a minority from the gun gas escaping the muzzle. However, when it comes to taming the kick I'm sure that every little helps!

Tony Williams: Military gun and ammunition website and discussion forum

 

[Fumbler]

Recoil starts as soon as the bullet starts moving and ends when all the energy is dispersed as either force on your shoulder, force in cycling the action, sound, heat, or whatever else the physisists say energy turns into.

Muzzle brakes work by redirecting exiting gas from the muzzle. The gun already starts to recoil and then gets counteracted after the bullet exits, but since the amount of time between the bullet starting to move and the bullet exiting is so small there's not enough time for the gun to move rearward far enough to push hard on you.

Adding weight simply adds more mass that must be moved and thus takes away energy that would have otherwise be put on your shoulder. Buffers don't take away any energy, but they do spread out the amount of time the force acts on you thus making the peak forces smaller. The result is a sense of having less recoil. Same goes for the springs.

The most effective out of what you listed is a muzzle brake but it will also make your gun loud as heck. Generally high pressure rounds do better with muzzle brakes than lower pressuer bigger bore rounds. Thats one reason pistol shooters use the high intensity 35 cals over the 45ACP in race guns. I have no personal experience with the AR platform or the 50 Beowolf, so hopefully someone else can add some info.

 

[TimRB]

"Could someone explain what causes recoil in a Beowulf AR and what is the difference between ways of reducing it? Which are most effective in reducing recoil?"

There are two things to look at--actual recoil and felt recoil. Actual recoil is what the engineers calculate, and your options to reduce it are limited: increase the weight of your rifle, reduce the weight of your bullet, reduce your muzzle velocity (probably by reducing the powder charge, which helps in another way as well).

Felt recoil is probably where you can do something useful. This is, obviously enough, the recoil that is clobbering your shoulder. You can reduce its effects by adding a recoil pad (to both you and your rifle). It may be beneficial to shoot in different positions. For example, shooting prone you get the full brunt of any recoil, but shooting offhand your whole upper body can move backwards with the recoil, reducing the punch your shoulder takes.

Hatcher's notebook has a very fine discussion of recoil, how to calculate it, and what to do about it.

Tim

 

[Murphster]

Call me a sissy, but I wear PAST recoil pads. I have a "regular" one and a no-fooling really thick one. They've kept me bruise free through four 45-70's and one .375 H&H and have probably kept my flinching down as well. They are cheaper than altering your rifle and won't have any bearing on a gun's resale value. I'd recommend one of these before having work done on the gun.

 

[Bullet]

Thanks for the info. I did some searching on the Internet too. I found a recoil calculator check it out at -

http://www.travellercentral.com/rules/ke.html

 

[Bullet]

A 50 Beowulf’s recoil shooting 335gr bullets at 1900fps is the same in opposite directions.

Bullet weight 335 times fps 1900 = 636,500
So
636,500 divided by gun weight 42,000grs (6 lbs) = 15.15 fps

My 6-pound rifle wants to travel back 15.15 feet in one second and my shoulder is what is stopping it.

Is this right?

No wonder I have a bruise.

 

[TimRB]

"Is this right? "

Yes. Momentum is conserved.

Tim

 

[Molon Labe]

Muzzle brakes work by redirecting exiting gas from the muzzle.

A muzzle brake works by transferring the momentum of some of the gas to the barrel, thus imposing a force onto the barrel in the direction away from the shooter. The direction of the gas exiting the muzzle brake is not important; you can design a very effective muzzle brake where the gas exits toward the shooter, and you can design a very effective muzzle brake where the gas exits away from the shooter.

 

[Tony Williams]

The direction of the gas exiting the muzzle brake is not important; you can design a very effective muzzle brake where the gas exits toward the shooter, and you can design a very effective muzzle brake where the gas exits away from the shooter.

Hmm. To achieve maximum effect, the gas should be diverted, as far as possible, in the opposite direction to that of the bullet - i.e. towards the shooter.

Let me spell out why this is. Suppose you have a high-velocity cartridge which generates 40% of the recoil from the escaping gun gas. If all of the gas is diverted to the side by the brake, then you will reduce the recoil by a bit less than 40% (impossible to achieve exactly 40% as no muzzle brake can be 100% effective).

But if you divert the gas to the rear, you not only stop it from adding to the bullet recoil but actually start counteracting it. With enough propellant, you can in theory entirely cancel out the bullet recoil - that's how most recoilless guns work, except that they divert the gas from the back of the chamber instead of the muzzle.

Tony Williams: Military gun and ammunition website and discussion forum

 

[Molon Labe]

Tony:

Sorry, but the direction of the gas existing a muzzle brake in-and-of-itself has nothing to do with reduced recoil. This is a very common myth amongst shooters, who (incorrectly) believe the gas must exit toward the shooter so as to "rocket" the barrel forward. Basic physics proves that this cannot occur in a passive system such as a muzzle brake.

Very High Power (VHP) Magazine, which is published by the Fifty Caliber Shooter's Association, ran a series of articles on how muzzle brakes work a couple of years ago. In the article the author explains in detail precisely how a muzzle brake actually works. I highly suggest getting a hold of this article. In a nut shell,

1. Gas has mass.
2. Moving gas has momentum (mv).
3. The muzzle brake contains surfaces that are not parallel with the barrel.
4. Some of the gas molecules hit these surfaces.
5. When the gas molecules hit the surfaces, some of their momentum is transferred to the muzzle brake, and thus the barrel. This imparts some forward momentum to the barrel.

And that’s how they work. But it’s not the end of the story. After a gas molecule hits a surface inside the muzzle brake, you want to expel it ASAP, else it will impede the flow of incoming gas molecules. So the muzzle brake must also be designed to expel gas molecules in an efficient manner (i.e. with minimal turbulence and back pressure). The actual direction these molecules are expelled is a function of the design, and (in-and-of-itself) has nothing to do with recoil reduction. Indeed, very effective muzzle brakes have been designed where the gas exits toward the shooter, and very effective muzzle brakes have been designed where the gas exits away from the shooter.

 

[Tony Williams]

OK, I understand where you're coming from. However, I would argue that the effectiveness of a muzzle brake depends on how many of those gas molecules hit the surface of the brake. I have read elsewhere that the most efficient form of brake would be very wide - rather like a plate fitted to the muzzle - so that as much gas as possible hits it and 'drags the barrel forward'. However, such a brake would also deflect much of the gas to the rear (I'm sure the shooter would notice a considerable increase in noise, at the least). By comparison, a brake which simply consists of slots in the barrel would deflect hardly any gas to the rear, but it would be less effective.

Tony Williams: Military gun and ammunition website and discussion forum

 

[Risasi]

Bullet

I tamed the recoil on my Beowulf.

I dropped a limbsaver on my A2 buttstock. That did the trick.

 

[Molon Labe]

I would argue that the effectiveness of a muzzle brake depends on how many of those gas molecules hit the surface of the brake.

While this is true, there are other factors of equal importance, such as the angle of the surface relative to the barrel axis. The most efficient angle for imparting momentum is approximately 90 degrees. However, this is not the optimal angle for efficiently exhausting the gas from the muzzle brake (it would cause a lot of turbulence and impede flow).

When designing a muzzle brake there are tradeoffs involved; when you optimize one parameter you will invariably decrease the performance of another parameter. Parameters include the following:

1. Quantity of captured gas (what you’re referring to).
2. Efficiency of momentum transfer.
3. Efficiency of exhausting gas from muzzle brake.
4. Discomfort of muzzle blast.
5. Size.
6. Mass.
7. Limitations due to material properties.
8. Disruption of internal ballistics environment.
9. Price.