Brake questions part II, six conclusions.

[tjensen]

Hi again friends.
After my post on muzzle brake questions I have come to the following conclusions.

1.
There is no need for a "wall" around the exit hole as there is no "sail" effect. I think that has been made absolutely clear. At least not a big one.

2.
The dia of the blow holes are not important, but to small holes can make some kind of high pitched sound wich is uncomfortable to the shooter.

3.
The only reason for the blow holes not to be 90 degrees is to to direct the noise away from the shooter and has no effect on the effectiveness of the brake.

4.
Exit hole should preferably be no more than ,020" over bullet dia.

5.
A chamber in a muzzle brake is not neccesary, in fact longer blow holes are better.

6.
Only reason for brakes not having blow holes on the down side is tho prevent dust blowing up under the barrel.

Now, maybe there should be a question mark after each of these statements but am I right or am I wrong?
I general.

Thanks again.

 

[mike in co]

newtons laws of motion...
if the exiting gas does not impart some of its energy into some surface of the brake....there is no braking.

yes you need a surface...or two...for the energy of the gas to expell some of its energy.

since the intial recoil is essentially straight back...you need a way of genertating motion straight forward....that would tend to imply a wall, or sail.....

mike in co

 

[4Mesh]

Hi again friends.
After my post on muzzle brake questions I have come to the following conclusions.

Are you sure it was something in the previous thread that prompted these???

1. There is no need for a "wall" around the exit hole as there is no "sail" effect. I think that has been made absolutely clear. At least not a big one.

Disagree 100%

2. The dia of the blow holes are not important, but to small holes can make some kind of high pitched sound wich is uncomfortable to the shooter.

Agree up to the comma. (btw, TOO small of holes...)

3. The only reason for the blow holes not to be 90 degrees is to to direct the noise away from the shooter and has no effect on the effectiveness of the brake.

Incorrect. The only reason not to go past 90 degrees is rules.

4. Exit hole should preferably be no more than ,020" over bullet dia.

I disagree. I'd go at least .020 / side over, at least.

5. A chamber in a muzzle brake is not neccesary, in fact longer blow holes are better.

So why does the military put em in the brakes on tanks? Furthermore, does the test data show any other results than recoil reduction. What is the goal of the brake? This is a benchrest forum ya know.

6. Only reason for brakes not having blow holes on the down side is tho prevent dust blowing up under the barrel.

HEY! We agree! But, typically only relevant for belly-shoot'n.

Now, maybe there should be a question mark after each of these statements but am I right or am I wrong?
I general.

Well, I'd give you a 1.5 out of 6.

 

[Boyd Allen]

I believe that as the bullet is moving in the bore, the recoil is caused by the pressure of the combustion gasses against the bullet. After the bullet unseals at the crown there is a jet of gas that acts like a rocket. By turning this jet of gas its contribution to recoil is reduced. The higher the muzzle pressure (slower powder, shorter barrel) the more pronounced a brakes effect will be. Anything that more effectively reduces the alternate path resistance to gas flow during the instant that the bullet is blocking the brake's exit hole will increase the percentage of gasses that do not follow the bullet and contribute to recoil. I believe that the most extreme examples of this are the "clamshell" style brakes, which are generally reported to give the greatest recoil reduction, be the loudest. I have had good reports, for hunting applications, on Holland, and Vias brakes. I would say that the Harrell brakes represent a tremendous value, are likely to be among the most dimensionally correct, and are of well proven design.

 

[tjensen]

4mesh.
Conclusions or not, there are obviously many opinions on all of these statements.
But they all fit with many brakes that work. However, why and how well they work is another thing and I just use what seems believable in the previous discussion.
For instance the comment by Jim S about the sail effect convinced me that its nonexistent, like putting a fan abord a sailboat.

I dont know why the military has chamber in theyrs but they also have big blow holes like the one that worked best for Roy B.

Why go over ,020 over bullet dia?

Would you go past 90 degrees if allowed? (no rules on that where I am) And if so why?

Regards.

 

[4Mesh]

I'm gonna guess that you didn't pick up on the "subtle hints of sarcasm" for Jim's posts. There was all sorts of good information (factual information) to take from that thread. Why in gawds name would you take stock in that which was so flawed?

His hose on the floor thing was so far off the mark, people just ignored it. Same with the sailboat thing... you gotta be kidding me.

There are no troubles making a brake work. Making one that does not detract from accuracy at a benchrest level is a different story. You ask if I would use one that vented past 90deg if allowed. Hell, I didn't use one at all, even when it was allowed. That's how much faith I have in em.

If you actually read what Jim said in the one post, he says one chamber doesn't help, yet goes on to say each one of his rows of holes is another chamber. Ah, so one doesn't but many do.

Hey, whatever. You believe what you like. Fact remains, you get to use the powder mass and that is all, and for the reasons I already posted. I just had to chuckle as I went back to that thread and read again. Jim makes a statement that is patently false, and you chime in and say, wow, when you explain it like that it all makes sense.




Ok....

 

[tjensen]

Well I see I have met another "knowitall" here by the name of 4mesh.
I never said that I was looking for a brake to use in benchrest and there are other rifles discussed here than benchrest rifles.
If you have anything costructive to say 4mesh I would be interrested to read it, honestly.
But no matter how many times I read your last post I cant see any sign of wisdom there, but of course I dont know it all like you do.
You must be really popular at the range.

I would really like some input from others also in languige that us humans understand.

 

[alinwa]

Yo tjensen,

since you seem intent on believing someone else's information instead of actually UNDERSTANDING the thang...... here's a link.

http://www.eabco.com/cssmb.html

It has some garbage, read the JP Howitzer description to find "However, some particularly vicious recoiling rifles such as pencil barreled WSMs... blah blah blah," but gener'ly they have it right.

PLEASE NOTE that the JP Howitzer brake description is otherwise SPOT ON.

I can't explain it better than they do without y'all's going off on "making a simple thing all complicated...."

Good luck all y'alls.......


(BTW, to others reading this who don't have a dog in the fight, LISSEN TO THE 4MESH GUY!!!!)

LOL

al

 

[4Mesh]

I never said that I was looking for a brake to use in benchrest and there are other rifles discussed here than benchrest rifles.

No, you simply asked in the gunsmithing section of a benchrest forum. Check the name of the forum. Down through the history of this forum, even when folks were not involved in BR, they have wanted answers that have no compromises with accuracy.

If you have anything costructive to say 4mesh I would be interrested to read it, honestly.

I and several others said plenty that was constructive, spelled constructive. You simply fail to read it.

But no matter how many times I read your last post I cant see any sign of wisdom there, but of course I dont know it all like you do.

The only wisdom is in the idea of going back and re-reading what people wrote, instead of whatever it is you took from what they wrote. Those two are not the same thing. Clearly.

You must be really popular at the range.

Don't really give a s*&^t one way or the other.

I would really like some input from others also in languige that us humans understand.

Spelled Language. I'm not sure what language you want it in. So I'll tell you what. Here's a site (IN MY OPINION) with THE definitive work on brakes. It's not in english but google, altavista, babelfish, etc, all do translation. If you truly want answers, why not go there and get them.

http://lutz-moeller-jagd.de/

Lutz has probably forgotten more about brakes than most of us are ever gonna know.

To save you a little time, Rückstoßbremsen translates to recoil brakes. That's the menu item you want.

 

[mike in co]

if purchance, you have little understanding of the process, but would still consider things that work, even if you do not know why......
take a look at the clam shell muzzle brakes on a typical commercial 50 bmg rifle......typically two large flat surfaces with extended walls which point backwards......
no drilled pretty holes.....
just something that works very well....gas impingement on the flat and redirected back and out.....

mike in co

 

[alinwa]

4mesh that's a good site. I especially enjoyed the tank silencers...... I thought I'd seen it all.

al

 

[lefty o]

It has some garbage, read the JP Howitzer description to find "However, some particularly vicious recoiling rifles such as pencil barreled WSMs... blah blah blah," but gener'ly they have it right.

that is funny. i never thought my mod70 featherweight 270WSM was a hard kicking rifle! LOL

 

[mike in co]

things not on motion tend to stay that way.
things in motion tend to stay in motion
for every motion there is an equal and opposite motion.
a gun at rest with a chambered round....not in motion, tends to stay that way.
when fired, the rapidly expanding gases tend to move the bullet down the bbl....this motion has an equal and opposite....what we call recoil.
( yes the gas has some mass and energy, but it is the moving of the bullet, that provides the recoil we feel.)
the gas continues to expand and continues to push the bullet forward.
the (some of) remaining energy in/of the gas can be used to reduce felt recoil.
it needs to run into a non-moving object, and expend some of its energy moving the object.
the simple answer is redirect the gas( but remember it is a gas and is trying hard to come to an equilibrium with it surroundings).
its moving forward and expanding.........let it run into a flat surface...and it can transfer energy..in effect pushing( against the flat surface) the gun backwards......
the larger the ports are the less likey the gas can do this again and push the gun forward.......
chambers, flat surface and large venting ports( and ues as little clearance as practical....)
i'd say some of your 6 basic assumptions are not good ones.

mike in co

.

 

[4Mesh]

4mesh that's a good site. I especially enjoyed the tank silencers...... I thought I'd seen it all.

al

Al, Lutz is connected in some way with Kurzzeit.com. Go there if for no other reason than the entertainment value. You may have seen some of their stuff before, but they change vids on a regular basis. Some of those things are amazing.

Mike, you might want to re-edit and change:

in effect pushing( against the flat surface) the gun backwards......

to
in effect pushing( against the flat surface) the gun forwards......Or pulling, as someone might contest...

 

[mks]

I believe that as the bullet is moving in the bore, the recoil is caused by the pressure of the combustion gasses against the bullet.

Boyd,
If I could help out here, without getting into the rest of this entertaining discussion, it would be to point out that if we could miraculously contain the combusting gasses without moving the bullet, there would be no recoil. It is actually the acceleration of the bullet and the gasses that cause the pressure force on the bolt face to be larger than the pressure force on the base of the bullet. The net rearward force on the bolt face causes the recoil.

All the best for the holidays,
Keith

 

[ultramagmed]

I believe that as the bullet is moving in the bore, the recoil is caused by the pressure of the combustion gasses against the bullet. After the bullet unseals at the crown there is a jet of gas that acts like a rocket. By turning this jet of gas its contribution to recoil is reduced. The higher the muzzle pressure (slower powder, shorter barrel) the more pronounced a brakes effect will be. Anything that more effectively reduces the alternate path resistance to gas flow during the instant that the bullet is blocking the brake's exit hole will increase the percentage of gasses that do not follow the bullet and contribute to recoil. I believe that the most extreme examples of this are the "clamshell" style brakes, which are generally reported to give the greatest recoil reduction, be the loudest. I have had good reports, for hunting applications, on Holland, and Vias brakes. I would say that the Harrell brakes represent a tremendous value, are likely to be among the most dimensionally correct, and are of well proven design.

In my opinion this post sums it all up!! I would like to add that; although I am fairly new to this whole game, I have installed nearly 50 Harrell's Precision muzzle brakes with no complaints. If you (after reaming) look through a Harrell's brake, the design of the drilled holes actually create a series of walls, sails or whatever the hell you want to call them. I believe this gives ample bearing surface as well as adequate side vent (they are drilled at 90 deg.) to reduce recoil to a tolerable level as long as the exit hole is maintained to be not more than .020 over bullet dia. as stated above. Smaller calibers create larger walls, sails or whatever the hell you want to call them (which also depends on the o.d. of the finished product; which also adds bearing surface) and are more effective (IMO) but, as Boyd stated, "The higher the muzzle pressure (slower powder, shorter barrel) the more pronounced a brakes effect will be." Just my $.00002, take it for what it’s worth.

Med.

 

[alinwa]

This whole "like a rocket" analogy is kinda'....... well, misunderstood.

A rifle IS a rocket IS a rifle IS a "reaction mass motor."

Not "after the bullet leaves" nor "before the bullet leaves" nor nuttin...... it's just a reaction mass motor.

period.

klik here to see rocket theory http://www.braeunig.us/space/propuls.htm

(and I say this knowing full well that to the average redneck use of the word "theory" acts to lessen the power of the argument just like doctors "practicing med'cine" makes people think they don't know what they're doing LOL!)


al

 

[mike in co]

boyd kinda has it....( the gas with no bullet has little affect on the rifle.....how much recoil do you get ie one fires a case of powder with no bullet ? no wad?...next to nothing)
look at some of the things going on.
the bullet has noticable mass, when it goes from no motion to in motion, there is then an equal and opposite motion...the rifle moves...we call it recoil.
when the bullet leaves the muzzle, the expanding fast moving gas..can only push against the air . it slows down and spreads out...dispurses...joins the enviroment with little effect.
when the gas as it leaves the muzzle and expands runs into something attached to the bbl it will have some affect on the rifle. so yes 90 degree holes work,,because the gas is moving forward and expanding, but a flat solid (less a hole for the bullet) surface or two works better. its an effecency thing...more surface area...two big flat surfaces and turning the gas or a series of small holes of which only the front side of the hole can impart rear motion...as soon as the gas is in the hole and still expanding it is putting (close) to equal force, as it continuse to expand) on all sides of the hole.
mike in co

 

[4Mesh]

What's being lost here is the subject of mass. And this is in part because there are some misconceptions about the pressures involved.

If I take a pound of R25 and pour it on the sidewalk and throw a match on it, there's a good likelihood the match will simply go out. That doesn't mean it's not flammable. If I light the pile of powder, it goes up slowly into a big roaring flame and takes what, 4 or 5 seconds to burn out? Now, the fact that there was no explosion does not mean energy was not released.

If powder is contained like it is in a chamber, and pressurized greatly, it will burn really fast and make a big ka-boom. If there is nothing in front of it, it will do just what it does in the case of the sidewalk experiment. You might even get it to form some pressure by having the powder at the back of the case push on the powder in the front of the case, and then go pop. Maybe enough even to fire-form a case, that is already so soft you could bend it with your fingers.

Hold a 10Ga double barrel with 3.5" magnums hard to your shoulder and pull both triggers. Now, reload it and hold the gun at your side with just your hands and do the same. The fact that you can hold it in one hand out in the open and give'er both barrels does not mean there was no recoil, it just means you didn't notice cause you were not holding on as tight.

How much reduction you have in recoil is absolutely proportionate to the mass of the powder and in what direction it leaves. Rules in most competitive shooting disallow the use of brakes that vent rearward, or clamshell brakes, due to the annoyance caused to other shooters. Not due to them not working well.

Earlier I gave an example of powder weight, bullet weight, etc, showing what recoil reduction could be expected. It's pretty simple. Of course, if there is no recoil to reduce, you don't reduce much. Such is the case with fire-forming without bullets.

A shoulder fired recoil-less rocket is a terrific example of a muzzle brake gone wild. Send enough go-fast-stuff out the back of the thing, and you can send the projectile out the front without getting blown to mars. In this case, the shooters beside you won't mind a bit. But the ones standing behind you are not gonna like it very much. (Think, vent holes on a brake)