Do muzzlebrakes impact group size?

[Buttermilk]

The Muzzle brakes effectiveness comes from the expansion of gas created by the burning of a solid mass of powder. As that gas expands, it propels the bullet down the barrel and out the muzzle. Science will tell you that a gaseous state of matter will occupy about 100 times the volume of the same substance in a solid state of matter.

This expanding gases exit the muzzle, still looking for more room to expand. As it exits the muzzle, it then encounters the baffles of the brake (assuming it's a side ported brake) and exert their force upon the brake. These gases also have a velocity (recoil calculations take this into account; some use a constant, but reality is it varies with powder, cartridge, etc.) as they escape the barrel. The brake redirects those expanding gases which in turn redirects the force vectors and reduces recoil.

I personally don't believe the bullet plays much role in 'forcing' the gases out the brake. If it were so, then the bullets stability would be greatly compromised as at that point the bullet is unsupported by the barrel - now the gyroscopic spin of the bullet helps here as well. I also think that a muzzle brake might very well 'assist' with accuracy by simply pulling some of the exiting gaseous matter away from the base of the bullet as both are exiting the barrel, thereby creating less potential for the gas to negatively affect the base of the bullet.

Would/Could a muzzle brake affect accuracy? I believe it could and does (as compared to no muzzle brake on same barrel). Whether the effect is negative or positive would have to be shown with testing that particular barrel. Some barrels may display no change while others might show increased accuracy, and yet others still might show decreased accuracy, and hence would need the load tuned for the barrel/brake combination.

The Browning BOSS and similar devices show how the effects of a device attached to the end of the barrel can influence accuracy.

 

[Pulpwood]

I'm sure they are others here with more input than I can give .

 

[J E Custom]

Suppressors are illegal in NY and I am not hunting with a brake so sounds like load development will happen without the brake on. Then, when I have time, I may work up another load for when the brake is on.

My recommendation would be to test with the brake because of the number of shots fired and the reduction in recoil making for a more pleasant experience during the process and a more apprehensive load testing .

Load velocity will not change with the brake or without it and the attention to position and trigger control improves without the added recoil. After the test with the brake you will be able to tell if or what the change is without the brake and decide which way to go much easier.

If a muzzle brake is installed correctly, It has no effect on the bullet. Due to harmonics and weight it may, effect the POI and the accuracy but My experiences have been for the better.

The low pressure of the air in the barrel ahead of the bullet has no effect on the accuracy or velocity or the performance of the brake because when compressed by the bullet it increases only by the volume of the bore. Depending on the type of powder (Single base or double base) the powder will increase in volume by 1500 to 1700 times the powder volume charge and reach very high pressures (Normal SAMMI pressures are anywhere from 46,000 Psi to 65,000 Psi).

This gas is released after the bullet is gone from the bore at a lower pressure (Normally 12,000 to 18,000 Psi) Maximum pressure in a barrel occurs between 1/2 and 2/3 the length depending on the powder and projectile weight and pressure starts dropping until it exits. If the barrel is to short to burn all of the powder efficiently and the gas is allowed to exit at maximum pressure, sound levels and muzzle flash will be terrible and for the most part unacceptable. This is the reason that brakes normally don't have any negative effect on the bullet .

J E CUSTOM

 

[FEENIX]

Not to sound stupid, but isn't the bullet out of the barrel and the muzzle break before the muzzle break has any effect on recoil?

With out the bullet there, what forces the gases to the side and through the break?

 

[cheechin]

A lot of very accurate rifles have muzzle brakes on them.

Adding mass to the end of your barrel will change the POI with a given load, but usually not by too much.

Normally when a muzzlebrake hurts accuracy is when the inner diameter of the brake isn't concentric with the bore.

 

[Hatrick]

Thank you Feenix. I am still in the thought that the bullet is gone before the break works. How does all the gases pass the bullet?

 

[toddc]

Adding any weight whether it be a brake or a piece of lead tape at the end of a barrel can affect group size and POI purely due to harmonics.

 

[J E Custom]

Thank you Feenix. I am still in the thought that the bullet is gone before the break works. How does all the gases pass the bullet?

It doesn't pass the bullet, the bullet is long gone before the gas escapes the brake. the reason is that the pressure is falling and bullet speed is increasing until it exits the barrel.

the reason the gas exits the brake with the bullet gone is simply differential pressure. The pressure inside the brake is somewhere around 15,000 PSI to 18,000 PSI and the atmosphere it no more than 14 psi average so the high pressure gas looks for the quickest way out with the least resistance. The bore diameter in the exit of the brake is much smaller than the port volume so it allows more of the gas to exit the ports. Best size for the exit bore of the brake is .020 thousandths larger than the bore. Best size for the ports is determined buy the load and the amount of gas produced.

The larger the exit hole in the brake, the less efficient the brake is because it allows more gas to escape out the front And more backward thrust is produced.

J E CUSTOM

 

[sconnierider]

I think you are looking at the issue wrong. In a nutshell, yes, screwing anything (suppressor, muzzle brake, flash suppressor) to a barrel will change the harmonics of the barrel itself. It might tighten up groups or open them up. The point is, you need to shoot with the same setup in the field as you do at the bench to achieve the same results. One can't essentially screw a weight to the end of a barrel and expect the same results as previously recorded.

 

[FEENIX]

Thank you Feenix. I am still in the thought that the bullet is gone before the break works. How does all the gases pass the bullet?

You are correct as JEC answered it. Pay closer attention to the behavior of the gas due to the MB design instead of the bullet. Because some of the gas were allowed to escape from the side ports as supposed to all at the muzzle; thus reducing the recoil.

Cheers!

 

[WildRose]

All,
Do muzzlebrakes impact group sizes of a particular load? I have heard they can impact POI but I am not finding much on if it impacts a loads group size. If so, do you see a tremendous impact on load size or just a little? For example, If I had a load shooting .5MOA with brake, and .6-.7 without that would not bug me too much but if I had .5MOA group go to above .8MOA then I would probably be upset. The reason I am asking is I considering buying a lighter weight magnum rifle and putting a brake on it for load work up and shooting for fun but ultimately I would remove the brake and re-sight in the rifle prior to hunting. I try to wear ear protection when hunting but once in a great while (especially treestand hunting) a deer will surprise me and there is no time to get protection on. Shooting a rifle in open woods, yes can be somewhat impactful on your ears, is nowhere near as bad as if you have a brake on it.

Anything can affect your group size when you make a change.

A well designed, properly installed brake however should do nothing but to help you tighten up your groups once you find the right load.

 

[WildRose]

Not to sound stupid, but isn't the bullet out of the barrel and the muzzle break before the muzzle break has any effect on recoil?

Most yes, but your physical reaction to the recoil often begins before the round is even touched off.

Anticipation of recoil is probably the number one factor affecting shooter accuracy.

 

[WildRose]

As the bullet travels down the bore it pushing all the air inside the barrel out ahead of the bullet , the break has an effect on those gases even before the bullet leaves the barrel ( any changes on a barrel effects the harmonics of that system) one way or another

There will also be some of the expanding gas that gets in the barrel ahead of the bullet sealing it off.

 

[WildRose]

With out the bullet there, what forces the gases to the side and through the break?

The air pressure ahead of the end of the brake. Energy seeks the path of least resistance. With a properly designed brake you're going to have at least 4-5x as much volume of gas escaping from the ports rather than the muzzle end because of the difference between port size and bore size. Add up the volume of the openings of all of the ports and compare it to the muzzle end.