Question for "rocket scientists, fluid Engrs. and other very smart shooters

[Baddog0302]

Brake designs , normally all 3 & 4 port "shark gill" brakes come with a pilot hole that is drilled out for the Cal. of bullet being shot.
When finished, this leaves a .330-.345 hole through the entire brake's length for a 30 Cal. weapon.
When fired, the gas's are funneled through the 1st ports, what is left goes through the .330 hole to the 2nd port, and so forth.
Some of the recoil reduction comes from a "jet" action from the gases exiting through the ports. The sharper/ higher the angle of the exit hole the greater the "jet" force .
In the example with the .330 hole through the brake the 1st port gets the majority of the gases.
My question is, if the bullet path hole, with the exception of the final exit hole were opened to 5.25" on a 5/8 x 24 thread thus allowing a more equal distribution of the gases to the 3 or 4 ports mean a greater reduction in recoil ??

 

[expiper]

Im the least educated guy on here,,,but if I understand your train of thought ,,,if the hole is big the gas can get ahead of the bullet,,,roger

 

[swd]

If expiper is the least educated guy here I'm probably tied with him, but I have made lots of muzzle breaks. I think what your trying to describe is a "chambered" break. The theory being when the back of the bullet gets to the last hole you get a big "puff" of gas out the of the ports. I have built both chambered and tight bore designs and both seem to work about equally well. But I have noticed that on big bore rifles maybe 375 on up chambers might have a slight advantage but more so with drilled hole designs, probably because they keep port pressure up more. I also don't subscribe to the thought of overly large exit diameters on non chamber breaks. I typically run my exit diameter around .008"-.010" total clearance and they work noticeably better. Hard kickers get more clearance depending on the bore size. .345" on a 30 cal is a lazy gunsmith or one that's stuck in the box.

 

[Baddog0302]

Im the least educated guy on here,,,but if I understand your train of thought ,,,if the hole is big the gas can get ahead of the bullet,,,roger

NO, as is pointed out below, I was talking about a brake with a "chamber" vs one with the same small hole all the way through

 

[gunsandgunsmithing]

IME, if the exit hole and brake design are the same, you'll be hard pressed to even measure any difference..much less, feel it.

 

[FeMan]

A larger inline hole would increase recoil and not reduce it. The ports allow discarge of gases on opposing direction (the gasses aren't perpendicular to the bore but close). As the gasses pass from chamber to chamber, they create felt recoil. The more gasses passed on the more felt recoil you would have. If your theory was true, it seems a single chamber would perform the best.

 

[DaveTooley]

It's been my experience that expansion chamber style brakes are more efficient, all things being equal. With that being said you can get the chamber too long and cause accuracy issues. High speed video provides the proof. Depending on powder type and charge weight gas will pass the bullet doing approximately 6-8,000 FPS for a distance of a few inches before the bullet exits from the gas. In open air that's not a problem but any chamber length approaching 1.5" is likely to cause problems. I stay around 1.25" max.

 

[Cold Bore]

...if the bullet path hole, with the exception of the final exit hole were opened to 5.25" ...

I'm following what you are saying in general, but a five inch bore/brake chamber/"bullet path" is moving into howitzer territory.

 

[BoydAllen]

For what it is worth, a friend who builds custom brakes for customers' rifles did an experiment, on a magnum, and for his design the brake with the chamber gave slightly less recoil reduction than the one that was the same diameter all the way through. This was not an all inclusive test, just one of each on the same rifle, with the same ammo. Back when he started out making brakes, he threaded the muzzle of one of his rifles and set about making and testing a number of designs.

 

[gunsandgunsmithing]

A larger inline hole would increase recoil and not reduce it. The ports allow discarge of gases on opposing direction (the gasses aren't perpendicular to the bore but close). As the gasses pass from chamber to chamber, they create felt recoil. The more gasses passed on the more felt recoil you would have. If your theory was true, it seems a single chamber would perform the best.

I'm as dumb as they come but I have done a lot of brake testing. Little is gained by eliminating the "jet" effect, overall. Making the id larger reduces the "sail" area of the port, thereby reducing effectiveness of the brake. We can debate about brakes all day, and which one is best..yada, yada. Bottom line is, there really isn't a lot od difference in the cheapest vs the most expensive brakes in terms of felt recoil..at least within general design categories, i.e., gill style or round with holes all the way around it. Yes, some are measurably better than others..some by a fair amount, measurably. But, when it comes down to felt reduction, which is really what matters most, there's just not much difference, regardless of price. That said, the run and gun competition shooters want the best(but usually buy what is most popular) because they are interested in fast follow-up shots(double-taps)and re-aquiring sight picture asap. That's about the only application where I really believe that one should invest much into which brake is the absolutely MOST effective. Fact is, they all work wonders at recoil reduction. We're splitting hairs in this discussion, IMO, that don't amount to much.
As I said before, many buy what is most popular anyway, or because mr. so and so says its the best. It's my experience that a brake should be bored about .020 over bullet diameter and the back edge of the first port be approximately 1.000" in front of the crown, for best performance from a recoil reduction standpoint, and that the ports should offer as much sail area as possible. Some are a little better at scavenging gasses than others with baffles that lean forward near the id and then backward nearer the od. This helps but also gets lost in the noise when it comes right down to feeling any difference.

FWIW, I've MEASURED many brakes' performance against one another, so this isn't theory or guesswork, including cheap brakes, expensive ones, and custom brakes that I made to test.

It's hard to beat this design., and it's cheap.http://www.muzzlebrakesandmore.com/Ported_Muzzle_Brakes.php --Mike Ezell

 

[JRS]

http://precisionrifleblog.com/2015/07/07/muzzle-brakes-recoil-results-for-6mm-6-5mm

 

[fredo]

http://bulletin.accurateshooter.com/2015/07/muzzle-brake-comparison-test-by-precision-rifle-blog/

 

[FeMan]

gunsandgunsmithing. I agree with you for the most part. I compete in tactical shooting and tracking shots by controlling muzzle jump is the primary purpose of a brake for me. Primary recoil (i.e. equal and opposite forces of mass and acceleration) can only be controlled mechanically. But controlling secondary recoil (the rearward acceleration caused by expanding gases, which I referred to as the "jet effect") is what a brake does. They don't eliminate the effect but they do reduce the pressure of the gasses exiting the bore longitudinally and thereby reduce recoil. Starving a jet engine of combustion pressure has the same result. My fluid dynamics classes were 30 years ago but I think I have that right. Some of the brakes are also excellent at controlling muzzle jump. Here is a great write up on which are better than others in that regard.

http://precisionrifleblog.com/2015/07/25/muzzle-brakes-ability-to-stay-on-target/

 

[gunsandgunsmithing]

gunsandgunsmithing. I agree with you for the most part. I compete in tactical shooting and tracking shots by controlling muzzle jump is the primary purpose of a brake for me. Primary recoil (i.e. equal and opposite forces of mass and acceleration) can only be controlled mechanically. But controlling secondary recoil (the rearward acceleration caused by expanding gases, which I referred to as the "jet effect") is what a brake does. They don't eliminate the effect but they do reduce the pressure of the gasses exiting the bore longitudinally and thereby reduce recoil. Starving a jet engine of combustion pressure has the same result. My fluid dynamics classes were 30 years ago but I think I have that right. Some of the brakes are also excellent at controlling muzzle jump. Here is a great write up on which are better than others in that regard.

http://precisionrifleblog.com/2015/07/25/muzzle-brakes-ability-to-stay-on-target/

Yes, for the most part, we agree. But, gasses released into the open atmosphere dissipate very rapidly and just don't have "much" jet effect because of open air and the sort time that they produce energy. Put a "sail" right where they release, and it can do a significant amount of work.

 

[madderg]

Yes, for the most part, we agree. But, gasses released into the open atmosphere dissipate very rapidly and just don't have "much" jet effect because of open air and the sort time that they produce energy. Put a "sail" right where they release, and it can do a significant amount of work.
If you don't think that escaping gas has much energy, place some 1/4 inch ply around it...then try to find the pieces.

 

[fredo]

Very interesting link, with incredible photos:
http://kuulapaa.com/home/highspeed/rifles.html

 

[gunsandgunsmithing]

Yes, for the most part, we agree. But, gasses released into the open atmosphere dissipate very rapidly and just don't have "much" jet effect because of open air and the sort time that they produce energy. Put a "sail" right where they release, and it can do a significant amount of work.
If you don't think that escaping gas has much energy, place some 1/4 inch ply around it...then try to find the pieces.

Your post makes my point. A brake works by pulling the gun forward. Nuff' said.

 

[DaveTooley]

tunnel vision

 

[FeMan]

We need to be sure and not violate the laws of physics here. This is a really good write up on the physics of recoil and how brakes work.

http://precisionrifleblog.com/2015/07/01/muzzle-brakes-recoil-primer-test-equipment-rifles/

 

[IdahoSharpshooter]

take a close look at the original design by George Vais sometime...