Shotgun Comps

[Singlestack]

I picked up a 1187 barrel from a guy that quit shooting open. The barrel has had the forcing cone lengthened, angle porting done by Ballistic Specialties, and a J.P. comp. All I can say is WOW!! The gun has almost no recoil now, kinda like a .410! I was skeptical about how much difference it would make but it makes a big difference! I had to open up the gas ports slightly to get it to run my gun, but I can now unload a mag tube as fast as I can pull the trigger and all the shots hit the same place!

All this might not make a big difference on a course of fire, but my body sure does like it

[Wap wap]

I disagree that comps or porting works on shotguns at least to any degree of differentiation a human to tell. A 1 oz slug weighs 437 grs of which with 19 grs of powder the ejecta mass is 446 gr. The powder and if the comp is 100% effective can only reduce the recoil velocity of the total weight of the gun which 1187 are fairly heavy compared to Benellis, by 19/437 or 4%. This is less than the a 1oz. wheel weight attached to the end of your barrel. Or less than 1/2 ft/lbs of the 25 ft/lb target load 12 ga. produces. Trap shooters more or less abandoned porting years ago (at least 10) and were the first to initially test it to reduce fatique in long matches. Most went to under barrel weights although once in awhile someone comes running in out of breath with a new discovery. Forcing cone can reduce recoil, but it also reduces velocity by reducing pressure.

[tightloop]

wap wap

It is not really reducing the recoil that much...we all agree...however it does reduce the felt recoil by directing the recoil impulse in a more straight back direction rather than back, up, and out at a pretty severe angle...and it does allow faster followup shots as the muzzle rise is really reduced....

[George]

Wap wap, I Hate to disagree vehemently, but I will here. The JP Recoil Eliminator does work very well in actually reducing the rearward recoil impulse. The JP Recoil Eliminator actually re-directs gas backwards just like a pistol, or rifle comp and the effect is not just noticeable, but striking. The brake attaches a few inches past where the gas ports are and it taps gas where the pressure is still very high instead of at the muzzle.

The recoil reduction here has nothing to do with ejecta mass of the projectile, but instead with the actual gas pressure in PSI generated behind the projectile. The gas pressure hitting the brake baffles is what does the job and this actually pushes the shotgun forward.

BTW, porting does reduce muzzle flip in shotguns too! Just go ask Patrick Sweeney if you would like to hear it from a more authoritative source.

The porting and the brake each accomplish different tasks and each one is effective in it's own way. I had the porting done first and the brake added later. The difference is striking as I mentioned earlier.

Sorry TL, but I am not one of the folks that agree with the result being slight. It really is a big thing when the JP Recoil Eliminator is added to a remmy.

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Regards,

[scooterj]

My 1187 was ported by Odie Wheat and the reduction of muzzle flip is very noticable.

[Singlestack]

Wap wap, I Hate to disagree vehemently, but I will here.

<{POST_SNAPBACK}>

Me too. I wish I could let you shoot my shotgun Wap wap, you would change your mind

[hoodhazard]

Where it really counts are those sub.25 second splits.If you can't get to that speed you probaly don't have any use for it.That's why bird shooters wouldn't be impressed by it.They shoot 2 rounds in sporting clays,skeet,but we shoot a target rich environment laying down a dozen rounds.Apples and oranges.If porting don't help why won't anyone let me shoot it as Tactical?

[TRUBL]

WHOOOOAAAAA...........Somebody better tell Browning, Weatherby, Parrazzi and a few other Trap gun manufacturers that porting doesn't work....as they still port their trap guns and Sporting clays guns to reduce fatige and muzzsle for for doubles shooting.

I have an XT trap and an XS special that came ported right from the factory....actualy, the fact of the matter is that more o/u guns are coming out ported than 10 years ago right from the factory.

Wapwap.....I think you will have to shoot a JP open shotgun before you make that statement. There are not many out there that will shoot much softer than one them.....there are some out there, but not many, and a lot less in 3 gun shooting.

Actually.....I would almost tend to agree that porting (not comps) would be tactically sound on a shotgun and not be limited to open class as it does keep the muzzle from flipping off target. (just I just start a new thread....or drift?)

[benny hill]

We shoot our limited guns target to target in about .018 splits & our open ones the same. Since we are not shooting double taps on targets but only one shot it does't really matter.

[XRe]

We shoot our limited guns target to target in about .018 splits & our open ones the same. Since we are not shooting double taps on targets but only one shot it does't really matter.

<{POST_SNAPBACK}>

Really!?!?! That fast, huh???? I knew you were hella good with a scattergun, Benny, but *wow*.... :lol:

[Wap wap]

I'm not stating that everyone won't have a different opinion, I'm stating my experience after 20 years of shooting sports. The pressure reached in any shotgun rarely exceeds 19000 psi which is very low and the ejecta mass does matter. 19 grs ejected at a velocity of 1200 fps, is just about the same as a 44 mag with a cast lead load. If you don't think it does remove it and see if your shotgun still works. A 44 weighs about 3 lbs and a muzzle break is barely noticable a shotgun weighs almost 8 lbs. almost 3 times as much, does that make the brake work 3 times as better? The amount of gas particles striking the baffles of the dams in breaks can only do the amount of work available in that much chemical energy. I have tried many different types of porting and muzzle breaks, most of the loads I shoot are 3" Brenneke slugs (1000's and as much as 5000 rounds a year in the type of speed shooting you do and 300-400 3 inch mag steel loads during duck season) in as fast as my 11-87 can operate its system. Even if the energy provided by the ejecta mass were as much as 5 ft/lb the energy to operate the gas system would be about 3 ft/lbs which leaves about 2 ft/lbs left for "muzzle breaking". With the 25 ft/lbs and up to 36 for 3" loads still only leaves 4% no matter how subjective you paint the picture. High dollar gun makers also make their guns in any color you want, I sure the blue ones don't kick as much either beside I don't think a Perazzi would work well in your type of shooting. The biggest problem with porting and brakes I run into is pattern distortion as the shotcup is allowed to be remoulded by the openings changing the shot pattern to outright slivering of the shot sleeve when using steel shot. I have no doubt many new and possibly useless devices will be developed by all branches of the shooting sports in the future, the one or two that survive make it interesting.

[Singlestack]

Wap wap, to be honest, my eyes glazed over with your first ejecta mass formula

You can crunch all the numbers you want to validate your theory but if you were to shoot my 1187, you would be scratching your head trying to find the flaw in your ejecta mass psi theory. The combination I described in my opening post works and my shoulder didn't need a calculator to figure that out.

I am in complete agreement with Mr Hill. Since we don't put 2 shots on the same target with shotguns, the reduced recoil/flip will matter little on most courses of fire. Kinda like faster cycling shotguns. I have never seen a target array for a shotgun where a faster than a 1187 cycling shotgun would make a difference. The reduced recoil/flip might help on a plate rack though.

[George]

Wapwap, your hypothesis does not meet up with the real world data that exists. In any scientific experiment that would mean a data re-evaluation is in order and a new hypothesis to be formulated and tested.

The ejecta mass velocity/impetus at the muzzle has no resemblance to the pressure exerted on a comp baffle 10 inches further up the barrel at an earlier point in the pressure cycle, or even a set of ports 2-3 inches back.

I refer to my JP braked and ported 11-87 as my recoiless rifle. Why, because it is basically without noticeable recoil. I can hold it in the open air without mounting it on my shoulder and shoot 2 slug A'a at 10 yards in a doubletap. Try that with an unported, uncomped shotgun of any type (gas or blowback). I doubt you would be able to shoot a second shot after the first one rips the stock out of your grip.

Once again, I vehemently disagree. In scientific process, I do not have to disprove that it works, I only have to prove that it works. To prove that it works, all I need to do is get you to actually shoot a shotgun setup like this with the lite ammo it is tuned to run with (tuning the gun and load are part of the equation) and you will wonder where you have been all these years.

I would certainly be willing to (and I believe Singlestack would also) let you shoot my JP setup 11-87 in any testing scenario you would wish. Look one of us up at a match sometime and check it out for yourself. I'm not from Missouri, but you know what I mean ;-)

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Regards,

[TRUBL]

WAPWAP....the only thing I agree with you is the that the 19grains (max) of the spent powder being hurled thru the barrel at say 1200FPS.....does not amount to much force.....however, the part of the equation that you are missing is the force of the the gas (also going at 1200fps) hitting and pushing up against a baffle.

It is not the spent powder hitting against the baffle that is reducing the recoil (ok, maybe the 1/4 lpb of force or so)....more so, it is the gas acting on that surface....literally pushing the gun forward....well, helping to counteract the recoil.

Think of it this way.....the baffle is a sail on a ship......the wind pushes against the sail to make the ship move. The more wind you have, the force is acting on the sail.

We will never convince you on this forum I suspect, but your theroy is lacking the most important piece of data.....wind force up against the baffle, you've never even mentioned it, infact, with the way you have explained it....a sailing could not move by wind force alone....think about that one.....I think that the only way to prove it to you is to have shoot one......and we will know we are right, you are wrong, by the look on your face when you shoot one.

[Wap wap]

I'm somewhat confused, I can shoot 3" Brennekes or any round in my 11-87 with only one hand without putting it to my shoulder and it has no baffles, ports or duhikees. (Beside I've tried most of them before) What is the baffle, port or brake for if it is not for reducing muzzle flip? to pull the gun away from you during the recoil cycle? I mentioned what you call wind force as the molecular colloison against the baffles (see post on compensators in open pistol of this forum) and concur this is a measurable vector force although not near as much force is available as is being given in these posts. My complaint is no one is putting any quantitative measurement on it. The mass ejecta is 2 parts consisting of the solid and gaseous part. The amount of force availbe to do work is a function of the pressure in megapascals times the surface area. The amount of recoil is a function of the mass ejecta and it velocity divided by the weight of the gun. The amount of pressure available at any port is a function of the it's size and the pressure (which is measure of the chemical energy at that temperature according to accepted thermodynamic theory) The fact that a gun doesn't recoil with light ammo pretty much answers its self, it has no recoil because you are shooting lite ammo. The only shotgun I had that didn't "recoil" was a Browning recoilless trap gun I had for several years. And, George, if you are wondering where I have been all these years it has been doing post grad. work in physics and shooting although I don't have my head stuck in the sand of all action shooting. Still confused though one of the post says no double taps and one says yes double taps. I will try to get the worksheet for this to upload, however I'm sure it well cause much glazing, moaning, and snickering. But on the other hand your posts cause the same in the physics lab in which I work. As a side note the cycle rate for 1911 types and 1100 are just about the same and at the upper limit of the reflex pattern in the human.

[George]

I said a "double tap" with it held forward in front of you and getting a pair of A's on an IPSC target at 10 yards in the process. You must have a very good grip on things to do that with full power slugs, I don't think I am interested in shaking your hand ;-)

Yes, the light ammo is part of reducing recoil, no one shoots full power 230grain .45ACP hardball to get some extra gas at the muzzle in a .45 comp gun. The light ammo alone does not remove all of the recoil and muzzle flip. In fact, I can use full power ammo and there is still a huge reduction in flip (from the porting) and recoil (from the JP mid barrel mounted brake). It just leaves more recoil behind than there is in the first place with the lite loads and removing the recoil is what it is all abaout here.

As far as ejecta mass goes, 19 grams is the material mass and if we were in a weightless vacuum, it would generate 19 grams of rearward impetus if it were tossed out the front at 1g of accelaration.

It is actually being tossed out the ports at whatever velocity the port size, amount of venturi effect at play and pressure envelope behind it say it should be (I am unable to express this in pure math, but I am sure you can sort it out for me). The pressure in the bbl reaches 17-20k in the first couple of inches of payload movement. After the payload has moved halfway down the bbl, the 17k (I will use the low end) of pressure (or heat) gets to expand to 3 to 4 times the volume, this drops the pressure (and temp). It is (this is where you will have to do the math) still going to be a fairly intense pressure bomb at this point. Allow a pair of small conical ports in the barrel to apply the venturi effect on the escaping gas and the velocity hitting the brake baffles is going to be fairly great. Energy = mass x velocity. Nuff said. The mass is multiplied by velocity in this case.

Do the math if you want to break it down, but it is not 19 grams of mass doing the job at a 1x multiplier and the projectile payload is only acting as a stopper in this relationship (it's inertia keeping the gas in check is all that we care about while it's still in the bbl).

I may not be a scientist with a doctorate, but I am a practicing technologist and I do understand how things work ;-)

BTW, the 1911 can be made to cycle almost twice as fast as an 11 sumthing shotgun if you put some nice trick parts in it. No big science there, just a little machining and tuning. The 11 series gas breathing shotguns cycle in .13 to .14 period The 1911 can be made to cycle as quickly as .08 with the proper ammo/spring setups.

The reflex patterns in humans exhibits quite a bit of variability at the fast end of the curve. Not all trigger fingers can twitch at the same maximum speed (as evidenced by the Miculek version when compared to mine).

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Regards,

[George]

Lets put another couple items of comparison on the table which helps us approximate the forces in question with probably fair accuracy.

The bolt on an 1100/11-87 takes about 4, maybe more pounds of force to unlock. This is just to unlock, not the entire action stroke (which is assisted by the rearward force from the cartridge case being pushed back). The gas acting on a piston after several deflections produces this rearward acting force from slightly smaller bbl holes about 5 inches earlier in the bbl from where the JP brake taps off. With an allowance for pressure reduction from a number of forces and a 50% loss by the time the baffles at the brake are hit and a further reduction of efficiency from the closed gas system, we could easily still have a pound and a half of force applied to each of the two JP baffles, which ain't peanuts in recoil reduction. The principle is the same as the one opening the bolt and the efficiency isn't that much lower.

Lets talk PF here, a 55gr .223 projectile travelling 3000fps produces a measured 160PF typically. 30% of 19 grains is just about 6.5 grains and that is a reasonable guess as to what proportion of available ejecta mass is being tossed at the JP baffle. Say it's going at 1200fps at that point. 1200x6.5= 7800, or 5% of the PF of a .223 at muzzle which is 860 ft lbs of energy in reality. 5% of 800 ft lbs is 40 ft lbs. Let's cut that by 75% just for fun and efficiency sake. There is still the potential of 5-10 ft lbs acting on the 1/2 inch square baffle flats.

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Regards,

[benny hill]

Since no one shoots a combat match w/o the gun to his shoulder, tightly, it really still does'nt matter.

[TMC]

When I've shot my limited 1100 next to my JP open 1100 with the same 3dram 1-1/8oz shells there's a noticable difference in recoil and muzzle movement. That's all the proof I need.

[Larry White]

Benny uses another formula. If you can point it faster + pull the trigger faster + have about 240 lbs of mass + a 24in. COG = all other formulas are moot. A ton of sheer will power dosent hurt either.-----Larry

[George]

Benny uses another formula. If you can point it faster + pull the trigger faster + have about 240 lbs of mass + a 24in. COG = all other formulas are moot. A ton of sheer will power dosent hurt either

ROTFLMAO ;-)

When I've shot my limited 1100 next to my JP open 1100 with the same 3dram 1-1/8oz shells there's a noticable difference in recoil and muzzle movement. That's all the proof I need.

I was going to suggest a test using a modified 11-87 bbl and changing to a stock same length bbl using the same ammo, but it looks like Todd has done it already. We just need to do it again with the buttstock against a pressure transducer and a strain gauge holding the muzzle down. Once the force numbers are in, the need to prove is over and the need to noodle on why is begun. I personally have my own hypothesis and explained it earlier: Energy = Mass x Velocity. The active mass is small but it does have some V.

The difference between a theory and a real world result is that a theory needs to be proved, but a real world result needs to be reverse engineered to see why it "works". We have proved beyond a doubt that it works, it is now up to science to measure and quantify the observed effect and correlate it with a theory that is proveable. The proof that it works is there. The proof that it shouldn't work is still a hypothesis and needs it's own proof.

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Regards,

[BillL223]

I won an Al's Custom Comp in a Bowling Pin Match and didn't own a shotgun to attach it to. I decided that shotguns might be fun and bought a Benelli M1, used this for bowling pin shotgun for a few years and got into 3 gun, bought a Benelli factory comp and started shooting Open. I have for the most part quit Open (still have my speedloaders and brackets for shotgun side matches), sold both comps, actually while still shooting Open. I don't miss them. In a match, I have shot a .15 split with slugs and got 2 hits on a swinger. I run speed shoots just as fast w/o a comp as with. Maybe Benny is right again.

[George]

The point isn't that they are needed to shoot fast, in fact a lot of the best shooters don't care one way or another. The point here is that they do have an actual effect. Whether that effect is needed is not the arguement here.

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Regards

[wsimpso1]

I got tired of reading the thread about half way down, so my apologies if I say something that has already been beat to death...

First, credentials. Two mechanical engineering degrees and five years as an R&D engineer at Remington Arms in the early 1980's. Why didn't I stay on? This northerner was not going to be happy in Little Rock Arkansas... So, I can understand Wap wap's commentary.

Anyway, what stopped me on this thread is that wap wap is talking about the 19 grains of powder at 1200 ft/sec... The shot and wad may be moving at 1200 ft/sec when it leaves the bore, and the momentum from it is transferred to the gun, and the 19 grains of powder gases in the barrel are only moving as fast as the shot and wad WHILE IT IS STILL SEALED IN THE BORE. What Wap wap is saying is that 19 (powder) is pretty small compared to 456 (shot and wad), but that tells only part of the story.

Once the wad clears the brake ports, (please, it is a "Brake", not a "Break") the gases leaving the barrel accelerate to much higher speeds before being redirected aft. If they did not do this, the gun would hardly puff as the ejecta comes clear. Even .22 LR match ammo has a report, so it apparently has energy left when the bullet uncorks the barrel.

Now, gun gas velocity off of the muzzle (or anywhere else) is going to be pretty close to the speed of sound in the gas. The local speed of sound in gas is a function of the local gas temperature. And the pressure and temperature are linearly related once you get past the first few inches of barrel. Once you are 6 inches down bore, pressure is past peak, the burning is pretty well done, and most of what is happening is expansion. Volume is increasing, and pressure and temperature are dropping.

Free gas velocities from nitrocellulose gun barrels can be anywhere from 2000 to 6000 ft/sec depending upon gas pressure (actually temperature) at the place where the gas is released. In fact, sealed gas velocities must go higher than this - if the gases could not go faster than 1200 ft/s, how would they push a rifle bullet to 3100 ft/s? Magnum rifle gas velocities are highest, pipsqueak loads are lowest, and shotguns with mid-barrel ports are somewhere in the middle, because the pressures are still pretty high where they tap off the gas.

So, a mid barrel port will have a several times the gas velocities at the brake, and thus several times the energy that Wap wap implies.

Now for the rest of the story...

While the contribution is bigger than Wap wap implies, it is still not so big as to completely nullify the impulse from accelerating the shot and wad to 1200 ft/sec. But, human beings being the clever types that we are, we try to adjust how we vent off the gas to not only get the most recoil nullification, but we also vent the gas in the direction to take off the part of the recoil that bothers us the most. Or at least we try to. The early ports did not direct gases backward, and the slots were thin things, not allowing the gasses to accelerate to full speed before being redirected. More modern brakes are designed to allow the gasses to do more work for us...

Once we get by the mechanics, which do matter, we can cover the last part - physiology. We humans are non-linear sensors. Small forces are hard to sense, but as the load goes up, we feel it in ever increasing chunks. So if you start with something that is just uncomfortable, and soften it up some, it can almost become a non-issue, not because it is zero, but because it is below our recoil threshold.

So, a shotgun brake can not suck off all of the recoil. But it can suck off some, and a lot more than Wap wap's math implies. And some recoil reduction may be enough to make you think that it is gone.

So, yeah, brakes can work wonders for the recoil wimps (I admit that my recoil threshold is low) but they do not help as much for those who have a higher recoil threshold.

Billski

[George]

Thank you Billski,

Brakes on shotguns do work, just not as well as on guns using metallic cartridges with higher initial pressures, but they do work and I have known that ever since I tried one on my shotgun.

The subjectiveness of perception is an issue that must be removed before an effect is measured, or this is the type of discussion that will result everytime ;-)

I would still like to see this quantified with an actual measurement test sometime. Nothing like measuring things in my book.

Thanks again,

Edited April 25, 2005 by George