Pointed Crown for rifle barrel
- Thread starter LC Tikka
- Start date
STS
Silver $$ Contributor
We (a hand full of BR shooters) did this test 30 years ago. We used flat crowns, recessed flat crowns, radius crowns, recessed "stair step" crowns, inverted crowns (your pointed crown) and maybe a few others that I have forgotten. Bottom line was it didn't make any observable difference what so ever as long as the crown was machined and finished well at the bore. The goofy looking stair step crown was left in place and produced a Unlimited 10 shot grand agg record for Art Fruend. It brings to mind the fact that bullets can make it through a suppressor that is designed to create turbulence and still be VERY accurate.
Yes "BUT" notice the direction of the lower right arrow. The flow sheared off which is flow separation and the pressure differentials created, causes a reversion of the gasses, which is really just dead flow or space. Then you get into laminar and turbulent flow and Reynolds numbers and Adverse Pressure Gradients if we really want to.
Someone with too much time on their hands could test designing muzzle brakes that work backwards.
Al, are you listening?By this diagram the gas would actually be directed back to the bullet, actually opposite of the perceived effect.
Dusty Stevens
Shiner
To reduce recoil you must slow the gas down, let the bullet pass it, then actually direct it backwards. Theres a reason muzzle brakes are designed like they are and thats the reason they work. Theres a chamber/s then a spot for the bullet to exit while not letting the gas go out with it. Theres lots of chamber surface area and length math involved but thats the basics
The OP's inquiry was relative to accuracy and not recoil.
Yes it does if you were worried about recoil. Stripping gasses from a bullet to affect accuracy is another matter.
There have been claims that silencers and certain brakes do in fact aid accuracy, but most of the claims are nothing more than hype to sell your brake that has a different look than the rest of the guys at the range.
Maybe the direction of the vents would not matter, but stripping gasses away in the same direction as flow travel works better than trying to reverse it, as is the case with 99% of all brakes.
This should make perfect sense if one bothers to read it in it's entirety.
To the best of my knowledge, which I admit is limited, the muzzle brakes work because of the laws of momentum and energy transfer.
The high pressure and high speed gas "particles" are traveling in the forward +X direction, which drives the recoil of the rifle backward into the -X direction. To boil it down to its most basic level, the energy of the muzzle gas in the +X direction equals the recoil energy in the -X direction. If you can bring the energy of the "particles" of muzzle gas to a lower level, you can decrease the amount of recoil.
Muzzle brakes do this by effectively putting a wall in front of the gases. The wall absorbs any energy the gas "particles" lose in the direction transfer out the sides of the brake. Because the energy in the +X direction is now lower, so is the recoil energy in the -X direction. As a result, the felt recoil is lower. The lower recoil is in direct proportion to the amount of energy the brake's walls can absorb by redirecting the gas "particles."
Roeder
Silver $$ Contributor
This is one of the better explanations of how brakes work that I have seen. Many shooters, gunsmiths, and even brake makers do not understand how brakes work. Many brakes are designed with features that are claimed to make them more effective but which actually have the opposite effect.
Sorry, I don't buy your terminology. You say the "wall" absorbs "energy" . How does this absorbed energy manifest? It has to go somewhere. The hot gas might raise the wall temperature slightly, but the residence time is a few microseconds as it is diverted so that cannot account for much "energy". The gas velocity after hitting the wall is slightly reduced because of any heat loss, but it will be nearly the same as the impact velocity.
Energy in classical physics has no direction unit associated with it. Momentum does. I think the simple explanation for the recoil reduction is that the wall strips some of the powder gas from the total ejecta by diverting the gas sideways. Any reduction in the ejecta mass will cause a reduction in recoil. That is all there is to it. It is easily demonstrated with a ballistic pendulum.
RWO
The redirection of the gas ejecta may cause a lowering of the total mass involved in recoil, but the force imparted to the muzzle brake to redirect these gasses acts against the force of recoil, lowering it considerably. While perhaps not scholarly correct, Jason's attempt at putting this event in layman's terms is quite understandable to the unwashed masses.
Roeder
Silver $$ Contributor
So you say that the high velocity gas being diverted by the "wall" does not impart any force to the wall itself? If you are correct, then a small diameter brake is just as effective as a large one. Whether you call it energy or momentum, the high velocity gas does indeed possess mass just as surely as if it were liquid and diverting the direction of flow imparts force to the diverter.
This is interesting! So I am actually an engineer and so I do realize that my explanation is very simplistic. I just didn't want to scare anyone away with equations!
I think RWO raises a good point but wouldn't it be true that mass is much less important for establishing energy than velocity?Energy = 1/2mv^2. So velocity is squared compared to mass. The mass of the total volume of gas is probably a few grams, if that. But it's traveling at 8000 fps as it exits the muzzle, so the amount of energy the gas has is massive.
Also, when an object (a gas, if you will) exerts a force on another object (a muzzle brake), it transfers energy. Super simplistic but true nonetheless. Like RWO said, it can be seen with a Newtons Cradle. The gas is most certainly losing a fair amount of speed as it hits the muzzle brake wall. It doesn't need to lose much to impart significant energy either. The energy goes into the forward movement of the gun.
FWIW You're correct that energy technically has no direction. I was merely using it as an understandable correlate for force. Since the result of the forces is energy transfer, I made the leap in my explanation to simplify it.
Roeder:
You're dead right that the gas has mass. The act of the brake redirecting the gases imparts a huge amount of force on the baffle of a muzzle brake. That force is what pulls the rifle forward instead of letting it shoot back with equal force to the muzzle gas. You are also correct that a larger brake can be more effective than a small one. I think the principle still applies - the larger brake has a bigger "wall" to absorb energy from the gas. If you look at high speed photos of small muzzle brakes on magnum guns, you'll see a good amount of gas still carrying a forward trajectory. A bigger muzzle brake is used when a sufficient volume of gas needs to be diverted such that a small brake can't handle it.
I think RWO raises a good point but wouldn't it be true that mass is much less important for establishing energy than velocity?Energy = 1/2mv^2. So velocity is squared compared to mass. The mass of the total volume of gas is probably a few grams, if that. But it's traveling at 8000 fps as it exits the muzzle, so the amount of energy the gas has is massive.
Also, when an object (a gas, if you will) exerts a force on another object (a muzzle brake), it transfers energy. Super simplistic but true nonetheless. Like RWO said, it can be seen with a Newtons Cradle. The gas is most certainly losing a fair amount of speed as it hits the muzzle brake wall. It doesn't need to lose much to impart significant energy either. The energy goes into the forward movement of the gun.
FWIW You're correct that energy technically has no direction. I was merely using it as an understandable correlate for force. Since the result of the forces is energy transfer, I made the leap in my explanation to simplify it.
Roeder:
You're dead right that the gas has mass. The act of the brake redirecting the gases imparts a huge amount of force on the baffle of a muzzle brake. That force is what pulls the rifle forward instead of letting it shoot back with equal force to the muzzle gas. You are also correct that a larger brake can be more effective than a small one. I think the principle still applies - the larger brake has a bigger "wall" to absorb energy from the gas. If you look at high speed photos of small muzzle brakes on magnum guns, you'll see a good amount of gas still carrying a forward trajectory. A bigger muzzle brake is used when a sufficient volume of gas needs to be diverted such that a small brake can't handle it.
Yes "BUT" notice the direction of the lower right arrow. The flow sheared off which is flow separation and the pressure differentials created, causes a reversion of the gasses, which is really just dead flow or space. Then you get into laminar and turbulent flow and Reynolds numbers and Adverse Pressure Gradients if we really want to.
It's ok to talk about that stuff if you want to. It's been awhile but I took a few classes in fluid mechanics in school and there's other engineers here that'll be able to keep up with what you're discussing as well
dcali
Bullet Maker
You don't even need to think about forces, energy, and where they act, or fluid dynamics, which is very complex in a brake. There's a simpler way to look at it.
What you need to know is that momentum is conserved. Momentum is mass times velocity. If the bullet and gas are moving forward, as is the case without a brake, there must be an equal amount of momentum imparted to the rifle going backwards:
mass of rifle x velocity of rifle = mass of bullet x velocity of bullet + mass of powder x velocity of gas
The powder is converted to a gas of a mass that is equal to the powder charge weight - mass is conserved. The gas moves faster than the bullet.
If you vent the gas sideways (with a brake), there must be an equal amount of momentum imparted to the opposite side. That's why brakes have symmetrical ports - to avoid torquing the rifle to the side. So the gas going out one side balances out the gas going out the other, and the net sideways momentum is zero. But all that gas takes away from the gas that would be going forward. So there is less momentum going forward, and therefore less going backwards (via the rifle).
The key is that the total momentum remains the same. The momentum in every direction of every part of the system must add up to zero, so the rearward momentum must be less if there is gas vented to the side.
What you need to know is that momentum is conserved. Momentum is mass times velocity. If the bullet and gas are moving forward, as is the case without a brake, there must be an equal amount of momentum imparted to the rifle going backwards:
mass of rifle x velocity of rifle = mass of bullet x velocity of bullet + mass of powder x velocity of gas
The powder is converted to a gas of a mass that is equal to the powder charge weight - mass is conserved. The gas moves faster than the bullet.
If you vent the gas sideways (with a brake), there must be an equal amount of momentum imparted to the opposite side. That's why brakes have symmetrical ports - to avoid torquing the rifle to the side. So the gas going out one side balances out the gas going out the other, and the net sideways momentum is zero. But all that gas takes away from the gas that would be going forward. So there is less momentum going forward, and therefore less going backwards (via the rifle).
The key is that the total momentum remains the same. The momentum in every direction of every part of the system must add up to zero, so the rearward momentum must be less if there is gas vented to the side.
Dusty Stevens
Shiner
It happens
As far I can see I think Alex Wheeler answered your question in terms of the direction to experiment with the idea i.e. radiused crown. I have no idea if it'll show any improvement or not but it's what I'd try to satisfy my curiosity about the idea. Here's a video illustrating the effect
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