Home Forums Hunting & Shooting Ask The Gunwriters Measuring Free Recoil

Do any of you writers or anyone know of someone that has a way to measure free recoil.We have as an offshoot of our detachable breaching tool developed a detachable muzzel brake for shotguns.This unit does everything that porting a bbl. will do and acts as a muzzel break by just screwing it in like a factory choke tube.Weight is 2oz.and everyone who has used it thought it reduced recoil by about 30%.Our local source Hodgdon's Powder Co. has no way to measure it but has urged us to get it done and get it on the market,they would like to buy the first ones.I don't want to make claims I can't back up.TIA for any help.

Doug:

I do not have a perfect mathematical answer for you. However, there is a gunsmith whom I see at the local range often. He specializies in muzzle brake installation. He has rigged a recoil measurement tool.

It is essntially a rifle rest on wheels. The rest is mounted on a "Slide Board." The Slide Board is marked in inches. The whole thing is then strapped to the shooting bench with bungee cords.

The rifle is mounted in the rifle rest and "locked down." The rifle rest is inserted into "Slide Board" which has been strapped down to the bench. A round is chambered and then the trigger is tripped (without holding the rifle--usually he uses a toothbrush while standing off to one side).

The rig measures how far back the recoil pushes the rifle. He does a before muzzle brake and after muzzle brake comparison. The goal is a 20% reduction in travel. (20 inches of travel before becomes 16 inches of travel afterward.) It is a neat device. He and his customers seem happy with the results.

Just my 2 cents.

BMT

A fellow named (IIRC) Astin in Arizona developed the easiest, clearest way that I've ever seen. He sent me -- and I published in Handloader or Rifle -- some of his very revealing photos.

� He attached three tiny "grain of wheat" type electric bulbs to (a) the muzzle, (b) the breech, and (c) the shooter's right earmuff for each pair of otherwise identical "before and after" or "with and without" rifles and shotguns.

� At night, with nothing but empty space for background, he set a camera on a tripod, aimed at the shooter in position to shoot.

� With the shutter open, he (or a helper) fired a flash that recorded the image of the ready shooter.

� With the shutter still open, the shooter fired.

� He closed the shutter and wound the film for another two exposures on the next frame.

� Each double exposure showed (a) the shooter ready to shoot, (b) a bright spot where each little bulb was lit (before firing), and (c) (after firing) three wiggly lines (one from each bulb) showing the exact route and extent of each bulb's upward and rearward travel -- very dramatic comparative records of the actual recoil with each rifle and shotgun, with and without Astin's excellent EDMed muzzle-brake ports.

If there's a better way, I'd dearly love to know what it is.

Ken & Doug,

That seems like a neat idea and I bet the pictures look really cool. Sounds like this would be a neat way to get qualatative results. But I would think Doug is looking for a more quantatative measurement. The bungee cord experiment offers, to the first approximation (spring constant), a linear comparison between between the braked and unbraked shotgun (F=kx). Absolute values for recoil may not be obtainable, but the difference between the two relative to each other will yield a percent difference.

Measurement in the photos is both very easy and very accurate. The scale of reference is built right into each photo, irrespective of how much it's enlarged (the distance between the bulbs on the muzzle and the breech is fixed, so it can be measured, recorded, and scaled). This makes the measurement of both actual recoil distances (vertical and horizontal) directly measurable in inches, which can then be translated into percentages.

Any added hardware not used in actual shooting complicates matters, gives only secondary and indirect measurements, and produces misleading and to some extent false results. The open-shutter comparison photos show the real thing and only the real thing -- directly measurable in real units of measure.

A series of such photos -- with more than one shooter shooting each gun with and without the brake -- would also show whether the actual recoil varies a little from shooter to shooter.

The photo method produces more and better results than you've given it credit for. Think it over.

BMT
Sounds like what I'm looking for can you put me in touch?Thanks
Dr.Howell
I
like your idea easy and inexpensive.Thank you

I concur that the Photographic records give very accurate results. But the method is useless if you don't have access to the range at night (I don't).

The "recoil roller" gives reproducible results (I have seen him get the same result round ofter round after round), and works fairly well. You are right in that the method does not show muzzle jump. etc. But it works well enough to please the clients.

The 'smith is Richard Buss: www.nu-world.com-muzzlemaster 541-349-1290 (from the business card I got in 2001)

BMT

Ken,

I'm not saying the photo method is not without merit, I'm sorry you took it that way. But I don't think it would be as reliable as a spring experiment. My justification for this is the fact you are using a human in the experiment and you have to agree that there are too many variables attributed to that person for reproducable results. Far more variables than a direct (non-human) method of mesure. The biggest would be how tense he is when pulling the trigger the 2nd, 3rd, or 4th time. Is that person allowing his body to react the same way everytime. I think the photo experiment is a neat experiment and perhaps better shows the difference to a perspective buyer of a muzzlebrake, but I still disagree that it would provide a better quantatative measurement.

All right, Avagadro (BTW, shouldn't that be spelled AvOgadro?) -- if you insist on eliminating the human (which departs from reality right off the bat, but we'll overlook that for the nonce), then you also should avoid introducing any other element that changes the behavior of the recoiling gun. A sled or slide and a spring or ballast certainly add complexity of exactly the same kind that you object-to when it's a human (a normal inclusion in normal shooting).

The gun has to be (a) supported in some repeatable fashion (as nearly naturally as practicable) and (b) free to recoil with the absolute minimum of unnatural influence from that support mechanism, whatever that is. For the test to be worth bothering with, it must be as faithful to normal shooting realities and the normal behavior of the recoiling gun as possible.

So hang the dang thing from a parallelogram of wires that make the gun a ballistic pendulum.

You need to realize and acknowledge that we're talking about two separate and disparate elements here -- (a) the method of supporting the gun and (b) the method of recording its movements in some workable fashion that provides accurate measurements. The open-shutter photo is still the best and easiest way I know to record and measure (accurately) the movement of the recoiling gun. How the gun is supported determines how realistic are the gun's movements -- and therefore its measurements.

The shooter who fires the gun from his shoulder is as much a part of the recoil complex as the gun or the cartridge. If he leans hard forward into the butt or pulls down hard on the fore-end, the gun recoils in quite a different manner from the way it recoils with a loose, limber shooter who "rides with the punch." For one thing, the loose, limber shooter gets spun a bit -- a lateral vector absorbing some of the recoil, in the same way that muzzle rise provides a vertical recoil-absorbing vector.

I vividly remember an afternoon in 1954 when my pal Wyatt Keith and I shot two boxes of heavy loads in his feather-light single-barrel 12-gauge. Short, stocky Wyatt leaned forward hard into the butt, and the recoil moved his shoulder straight back a very short distance. At 6' 1" and about 135 pounds -- and shooting so loose that each round turned me to the right several degrees and bent my torso backward from the waist -- I appeared (to Wyatt) to be taking a lot of abuse. Five rounds left Wyatt's right shoulder so sore (black and blue) that he could barely drive his Buick home. I shot the rest of the two boxes of heavy 12-guage shells and never had a moment of pain.

No Ken ... AvOgadro is Amedeo's last name ... My handle is AvAgadro for reasons that have nothing to do with this post. About once a year someone tries to make me look stupid with that fact, must be that time of year again.



ANYTIME one can remove the human factor when making a measurment it typically only serves to enhance the measurment. Unless of course your measuring humans <img src="/ubbthreads/images/graemlins/smile.gif" alt="" /> The human factor will introduce human error. Lets use your friend (Wyatt Keith). I would be willing to bet that he didn't fire that fifth shot in the same fashion he fired the first. Also, a person isn't a spring, you cannot assume given a certain person's shooting habit, that a round that moves him back twice as far, had twice the recoil ... you cannot tell me a person has a linear response to force ... Such as a spring (to an first approximation <img src="/ubbthreads/images/graemlins/grin.gif" alt="" />). A person when firing a shot moves in 3-D (as you pointed out), your camera can only record in 2-D, unless you are also taking pictures from directly above the shooter also.



I agree that your picture method can be used to show the qualatative effects of recoil on a person firing a rifle with and without a muzzle brake. We are trying to measure differences in recoil ... not people. I still disagree that it is an accurate means to measure the relative difference in recoil from a rifle with and without a muzzle brake.



The open-shutter method may be the best way you know. That's fine with me. We can agree to disagree.



BTW .... I did think about it! I don't post rubbish that I think will be blasted out of the water, If I posted it, its because I thought about it. Except my jokes about Loggy <img src="/ubbthreads/images/graemlins/smile.gif" alt="" />



Good Day

Doug, the scientific way to "measure" the recoil is to place an accelerometer on the butt of the weapon orientated to the direction of recoil and then touch off a round. The sensor output will provide the true acceleration of the sensor. Knowing the mass of the weapon can be used to provide the values of interest.

This measurement will reveal what many individuals have eluded to when talking about heavier rifles "kicking" less than others. The peak acceleration and the time the gun accelerates (into you shoulder) are key in your understand of felt recoil. The longer the duration the more the recoil will feel like a push. The area under the curve (energy) will be the same for the same cartridge regardless of the stock/weight/muzzle break configuration but the peak acceleration and the duration will be less.

If you want to get fancy: place a second accelerometer on the front of the stock and you can quantify the "recoil reduction" of a stock/recoil pad system.

All mechanical engineering universities will have this equipment and they will most likely perform the experiment for a donation. They may also make some suggestions on how you may improve your design. Good luck Rick

I will not take sides, bescause I would only make myself look even more foolish than I am; however, I think you're talking about Tom Aston (with an O, I think), of Keeper-EDM Specialties, PO Box 959, Clarkdale, AZ, 928-634-2100.

A good friend of mine has a Model 70 .300 magnum with Aston's Keeper muzzle port. He swears that it reduces felt recoil considerably without really increasing muzzle blast.

I use Grandpa. Let him shoot the thing. If his teeth stay in his mouth then the recoil is mild. If he loses his upper plate it is stiff. If both plates go it is a bad cat.

BCR

<img src="/ubbthreads/images/graemlins/grin.gif" alt="" /> <img src="/ubbthreads/images/graemlins/grin.gif" alt="" /> <img src="/ubbthreads/images/graemlins/grin.gif" alt="" /> LMAO

BMT

<img src="/ubbthreads/images/graemlins/grin.gif" alt="" /> <img src="/ubbthreads/images/graemlins/grin.gif" alt="" /> <img src="/ubbthreads/images/graemlins/grin.gif" alt="" />

Bmt,Thanks I got ahold of Mr.Buss he is sending plans and pics.I will post results I'm also going to ceramic coat some of his brakes.

Boise where can I find an accelerometer?

BCR can I use any Grandfather?Are the tests done with or without Fix O Dent? Are the results repeatable?
Could I just use my wife and then check for loose fillings or do I have to get her false teeth?Sorry for all the questions but I want to get it right <img src="/ubbthreads/images/graemlins/grin.gif" alt="" />.

BCR,
If I missed anything let me know I figure if I use the wife method I only get 1 shoot.!!!! <img src="/ubbthreads/images/graemlins/wink.gif" alt="" />

Doug, Seabond, always use seabond, more consistent. Wouldn't use wife. Got to live with wife. Use Grandpa. When your through with him you just take him back to the home.

BCR

If you're testing a really big kicker, make sure the brakes are locked on Grandpa's wheel chair.

Doug, sorry if my typing is shaky but I'm still chuckling over the earlier posts. Those boys just aren't very scientific, they should have suggested using a stop watch to time how long it took grandpa to regain his focus then they could chart the...... <img src="/ubbthreads/images/graemlins/grin.gif" alt="" />

If is easy to locate accelerometers by doing a web search http://www.hotbot.com/default.asp?q...&tab=web&provKey=Inktomi . They are relatively inexpensive (~$20) compared to the signal analyzer needed to interrupt the sensor output. May I again suggest you contact your local area university�s mechanical engineering department and ask if they are willing to perform the experiments or can recommend someone that will.

If you are determined to make the measurements yourself and only want to make statesments as a percentage of difference then you may get by with an amp and a scope.

We used a similar technique while I was in school to debunk ski manufactures' claims of damping ability of various models.