What evidence supports the claim that a dual recoil spring reduces recoil?

[gasmitty]

Q: Anyone know the definition of an "Engineer"?

A: An accountant with no personality.

I take offense. I don't do accounting!

[DefensiveCarry.com]

[marcclarke]

I did a blind test with coke one time and I liked the Pepsi better.

I can tell Coke from Pepsi from Dr. Pepper simply by smell.

So what?

Some people over think, to try and reduce felt recoil is in the way you hold the gun and transfer the energy. I think making a super spring is a selling point. Recoil management is a better answer; learning to control recoil is a better way to go because a 357 revolver has no double spring in it

Webley once made a semi-automatic revolver that rotated the cylinder automatically as the frame and cylinder recoiled backward along a slide rail atop the grip and trigger assembly. The cylinder had an external grove that ran on a peg protruding from the top of the stationary grip assembly. IIRC, there were springs to retard the rearward motion of the barrel, frame, and cylinder assembly. Same discussion as we were having here.

https://en.wikipedia.org/wiki/Webley...matic_Revolver

800px-Webley-Fosbery_1837.jpg
If your low-tech .357 doesn't rotate its cylinder and cock its hammer for you, you clearly need to get one of those semi-automatic Webleys. :-)

[Bongo Boy]

You have any particular accelerometers in mind? I can do the interface and data collection with either a microcontroller or computer. Just wondering if you had anything in mind for accelerometers and/or how/where to mount them.

Oh gosh no, it's been so long since I've even seen this stuff I wouldn't even know what's currently available. It's been so long, in fact, that when I wrote "x-y accelerometers" what I actually pictured in my head was strain gages.

What I was thinking about in instrumenting the frame, and I could be wrong, is that if you just look at the slide then you have do a bunch of modeling to look at the actual frame trajectory. Simple modeling, but indirect just the same and I certainly couldn't do it anymore. So, with the frame instrumented I don't actually care what the slide is doing--we'd be looking directly as what the net result of the slide's motion is.

So don't you have a parts drawer full of tiny little micro wireless accelerometers with programmable range that you just cement onto the gun and then hit a 'Go' button somewhere? You know, bada bing, bada boom?

One of these would be pretty cool:



This one includes a number of expensive features that aren't needed (triaxial, extended range wireless, multi-sensor clock synch, etc), but some of the wired digital ones from Summit would of course be more reasonable, if not still ridiculously cool.

[Tangle]

[QUOTE=Bongo Boy;2149196]Oh gosh no, it's been so long since I've even seen this stuff I wouldn't even know what's currently available. It's been so long, in fact, that when I wrote "x-y accelerometers" what I actually pictured in my head was strain gages.
There are some solid state accel units now. Let me look around a bit more.

...What I was thinking about in instrumenting the frame, and I could be wrong, is that if you just look at the slide then you have do a bunch of modeling to look at the actual frame trajectory. Simple modeling, but indirect just the same and I certainly couldn't do it anymore. So, with the frame instrumented I don't actually care what the slide is doing--we'd be looking directly as what the net result of the slide's motion is.

Plus wiring to sensors on the slide could be another level if complication.

...So don't you have a parts drawer full of tiny little micro wireless accelerometers with programmable range that you just cement onto the gun and then hit a 'Go' button somewhere? You know, bada bing, bada boom?

LOL - I'll look again...

I'm a little concerned about that 'cement' to the frame. How would you get it off?

I'm pondering how one might deal with the rearward motion in the presence of gun rotation (muzzle rise). I'd have to give this some more thought - but I'm not so sure the X-Y forces plus calculating the resultant force of the X-Y forces would give an accurate picture of the acceleration forces. It may be that a rotational accel. sensor would be needed too.

[Bongo Boy]

I'm a little concerned about that 'cement' to the frame. How would you get it off?

I'm pondering how one might deal with the rearward motion in the presence of gun rotation (muzzle rise). I'd have to give this some more thought - but I'm not so sure the X-Y forces plus calculating the resultant force of the X-Y forces would give an accurate picture of the acceleration forces. It may be that a rotational accel. sensor would be needed too.

We'd mount with cyanoacrylate to a well-polished surface--a tiny blow with a mallet and nylon block would pop 'em right off. But, in those cases the acceleration was in a direction normal to the surface cemented--cyanoacrylate is pretty good in tension, no so good in shear. But...see below, no need for this.

I thought about torque, too, but really, I think it can be safely ignored for perceived recoil, and also with the assumption the devices we're investigating have no material impact on rotation. I think looking at this in 2-dim is more than adequate. So, at the maximum displacement of the gun, rotation is still only a few degrees really, and the whole acceleration story is all over with by then anyway. I believe that during both the initial impulse, when the slide jams to a stop at the rear, and even when it slams forward into battery...rotation is still pretty small and cos(small) = ~1.0 well within the noise this system will have.

The sensor I showed above, though, is truly way over the top and still probably too big to mount directly. Seriously now, I'd mount it to an accessory adaptor designed to go right on a Picatinny and not even worry the slide at all--just look at what the gun frame is doing. If it's not doing anything differently between Case A and Case B (that you can measure), then whatever magic micro-plasma-condenser-module you put in the slide isn't doing anything.

[Tangle]

...I thought about torque, too, but really, I think it can be safely ignored for perceived recoil, and also with the assumption the devices we're investigating have no material impact on rotation. I think looking at this in 2-dim is more than adequate.

That might do for comparisons on one gun, say a G17. But we would inevitably want to try it on a Sig P226, or even a G19, etc. The P226 has a higher bore and hence would have more muzzle rise (rotation).

Muzzle rise or lift would take the X-Y senors 'off' axis producing lower readings in both axes. The output caused by rotation would be indistinguishable from 'on' axis acceleration profiles producing the same X & Y accelerations.

However, I think with one X axis and two Y axis sensors mounted about a inch or so apart would give one rotational data as well X & Y data. I think, one could almost calculate the rotational profile.

...Seriously now, I'd mount it to an accessory adaptor designed to go right on a Picatinny and not even worry the slide at all--just look at what the gun frame is doing. If it's not doing anything differently between Case A and Case B (that you can measure), then whatever magic micro-plasma-condenser-module you put in the slide isn't doing anything.

I've been thinking about the accessory rail mount too, but Glock claims frame flex causes significantly reduced recoil. I think it's sales bunk myself, but there early problems with Gen 4s not shooting reliably with WMLs mounted. It was theorized although never proven, that the metal lights altered frame flex and hence the reliability. And that'd be ok too with a single gun, but I'm pretty sure, to go to this much trouble, one would want to compare recoil characteristics of different types and weights of guns, etc.

While something like this couldn't do it all, it would be nice to see how attaching a light/laser to a handgun affects recoil.

I also thought about replacing a grip, e.g. 1911 or Sig p series with a 'sensor grip'.

[Bongo Boy]

I thought you were referring to rotation about the bore axis, not the rotation you'd see from the side due to recoil. For everything in a single plane, I believe we only need biaxial, x-y. BUT, I made the mistake of assuming we know were the cg of the gun is. This thinking was messed up on my part--way too complicated. I don't want to model a non-rigid body in free space to back out its trajectory to then back out the acceleration I care about. Whew--what a nut.

I lost sight of what we wanted, I think. Imagine the gun mounted on a free-rolling carriage. One degree-of-freedom only, linear, parallel to the bore axis. Carriage or 'sled' is stopped after the cycle completes by a damper. Don't instrument the gun at all. Instrument the sled, one axis accelerometer only.

Every gun you mount has exactly the same conditions, same instrumentation, and all you're trying to do with a given gun is look at the impulse profile between test cases. While it has only 1DOF, we're not trying to model anything...we're just trying to distinguish between two cases where the ONLY change is the magic recoil reducer vs stock recoil spring. We do this by choosing one axis of acceleration that's influential in perceived recoil.

While heavier recoil usually means more muzzle climb for a given weapon, I think the bulk of the rearward portion of the firing cycle is over before the muzzle rises appreciably--much of the perceived recoil (the unpleasant stuff) happens before the muzzle climbs much, I'm asserting. So, both our measurements and our constraints on the weapon have us covered in the important part of the cycle--the first 'few' milliseconds.

Now we have a system that can actually be built, instrumented once, and used for any handgun. No question of differences in instrumentation, human intervention, etc. Clamp the gun in, remotely trigger it. Done. Actually you could use a fairly good-sized mass on the sled to reduce it's length and the need to stabilize it, and all you'd be doing is scaling the accelerations down, in effect.

I have a hunch that almost all recoil that we actually care about and would like to reduce happens to us before the slide has even moved a millimeter, and that recoil mechanisms of any kind have no impact whatsoever on it. Muzzle climb, an outcome of recoil that we definitely care about, may be another matter though.

I've been thinking about the accessory rail mount too, but Glock claims frame flex causes significantly reduced recoil. I think it's sales bunk myself...

...and aliens came here to build Stonehenge. Bunkum for the masses.

[Tangle]

I considered the 'sled' a long time ago, and finally gave up on it for a number of reasons. The clamping of various guns is more complicated than one would imagine. E.g. different widths, different shapes, etc. There would have to be some compliance for muzzle rise. If that's not accounted for and measured, we can't be sure how a rigid, non-rotating mount would impact rearward acting thrust forces. Also, muzzle flip is a part of recoil. Guns like Sigs, etc have a higher bore center-line and would cause more muzzle flip than say a Glock. I've found that the additional muzzle rise softens the 'felt' recoil.

Any substantial moving platform with essentially frictionless linear bearings would add significant mass to a gun, the smaller the gun the more affect the sled mass would have.

I really like the accelerometer approach. It adds very little mass and essentially no constraints to the gun except the shooter's hand, and that's the situation we really want to know about. Still thinking.....

[WD54241]

In the reality of physics, the only things that can actually "reduce" the recoil force of a standard, closed-breech weapon are to either increase the weight of the weapon, decrease the weight of the bullet/projectiles, or decrease the propellant charge.

"Apple-knocker" Newton's law brushes the surface by starting out with "any action will generate an equal and opposite reaction" which simply means that generation of a sudden explosive force that is confined between two objects (propellant ignition between bullet and weapon) will apply an equal force against both objects that tends to push them away from each other in opposite directions with the same degree of force.

Obviously, there are other physics principles involved or your .44 magnum handgun would come smashing back through your body at 750fps while the bullet went in the other direction at 750fps at a total of 1500fps velocity of their departure away from each other. What keeps that from happening is mass/inertia physics which involve only the "inertia of rest" when considering recoil force. The rule there generally states "an object at rest will tend to remain at rest and resist any force to set it in motion with an opposing force that is directly proportional to the mass (weight) of the object". You can quickly test that law by forcefully kicking a soccer ball and see how far it flies away - now, deliver the same forceful kick to a bowling ball and note which one of them resists being moved with such a force that it will break your toes and only move a few inches at best.

Since the broken toes after kicking the bowling ball are an indication of an "equal and opposing force" that are directly proportional to mass/inertia, consider the ratio between the bullet's weight and the weight of the weapon when the same force is applied between them. Obviously, the weapon's much higher weight and inertia of rest will instantly oppose the force trying to move it which, in turn, re-directs that force against the much lighter bullet to send it flying away at 1500fps while the much heavier weapon only moves to the rear at a few thousand times less speed and force.

Making the weapon heavier or making the bullet lighter will reduce the recoil force even more because the ratio of weapon weight/mass to bullet/mass has increased. Using a heavier bullet or decreasing weapon weight will reduce the mass/weight ratio between weapon and bullet which will result in more recoil force. Increasing or decreasing the propellant charge is a no-brainer on recoil changes since there's more or less force being generated.

After considering the physics laws of actual recoil force as being a "constant" with any particular weapon using the same weight bullet and same propellent force, there is nothing that can further reduce the level of that force. However, the effects or "feeling" of that recoil force CAN be reduced by spreading its application out over a longer period of time. Consider laying on the floor with a box on your chest while someone on top of a 6' step ladder drops a 50-pound bag of sand into the box (major owwieeee, broken ribs, etc.). Now consider that same person slowly pouring that bag of sand into the box on your chest; even though you're still taking the same amount of total weight or force against you, it's being applied at a much slower rate which does reduce the "feel" (and even injury) over it being applied all at once.

Dual springs, recoil pads, and all other such "recoil suppression" devices don't actually reduce the amount of recoil force in itself; but they do make that same amount of recoil force considerably more comfortable and manageable by spreading its application over a longer period of time.

Well stated, I understood what you said.

[Tangle]

My original response to this, "...Dual springs, recoil pads, and all other such "recoil suppression" devices don't actually reduce the amount of recoil force in itself; but they do make that same amount of recoil force considerably more comfortable and manageable by spreading its application over a longer period of time..." was how does a dual spring create more time? I never got an answer to that.

The statement is not correct. If a recoil suppressor increases the time, then the recoil force, i.e. the recoil force experienced by the shooter, is in fact reduced. This is based on the definition of impulse, i.e. force-seconds which in turn relates to momentum.

The concept is correct, but it is not force that remains constant. Plus, anything that absorbs energy from the recoil pulse can reduce the recoil, e.g. the rotating barrel in a PX4. It takes energy to rotate the barrel. The energy lost in rotating the barrel subtracts from the recoil force.

[phoenix5]

[From an engineering perspective, this claim is questionable. The simple purpose of the recoil spring is to decelerate the slide to a stop and then return it to the closed position. Since the energy imparted to the slide is fixed, i.e. controlled by the mass and energy of the bullet, AND the distance the slide has to stop in without dead-ending on the frame is also fixed, a DRS has to absorb the very same energy, motion, and velocity in the very same distance as a single spring does.]

Hello

You are mixing energy with force. Your analysis assumes that the single spring is strong enough to stop the slide before collision between the slide and frame. That is hardly the case. The design of SRS usualy allows just that to ensure reliability for different loads. The collision is resposible for most of the recoil force. As an engineer you may recall that force is not the energy but the rate of change of momentum which is high when you have collision between the slide and the frame in the case of single spring. For dual springs, the first spring is soft to insure dispatching the case. Once that happens, the second spring is hard enough to gradually stop the slide before colliding with frame. That gradual stopping of the slide reduces the recoil force (as compared to collision)

Incidentally, the gradual stopping of the slide using the second spring also improves reliability because it eliminates the wear and damge due to slide and frame collisions of a SRS.

[Tangle]

We cannot assume the spring does not stop the slide before it hits a stop. Range loads may not have enough power to force the slide to full travel.

The singe spring can either stop the slide from contact with the frame or it cannot. The very same is true for a dual spring. It's a matter of controlling where the last of the slide motion occurs - uniformly throughout the slide stroke or at the very end. There's no doubt one can put a strong enough single spring in to stop the slide IF a dual spring can unless there is a space issue.

How are we mixing energy with force?

[gunthorp]

Rotation of the gun about the vertical axis during recoil seems to soften the perceived recoil, perhaps by stretching out the recoil time or involving different parts of the hand. What about rotation about the horizontal axis? From my 440gr cast engaging the rifling, the 500 twists significantly as it comes up. All spinning bullets will exert some counter torque to the frame. What this has to do with dual recoil springs, I don't know.

[Tangle]

Rotation of the gun about the vertical axis during recoil seems to soften the perceived recoil, perhaps by stretching out the recoil time or involving different parts of the hand.

That's been my experience. E.g. with a given load, Sig P226/9s always seem to recoil softer than a Glock. Of course some of that is that the P226/9 weighs more than the Glock. but I think some of it is also exactly what you're saying. Still that has little, if anything to do with single or dual or triple springs, but it's certainly worth pointing out.

...What about rotation about the horizontal axis? From my 440gr cast engaging the rifling, the 500 twists significantly as it comes up. All spinning bullets will exert some counter torque to the frame. What this has to do with dual recoil springs, I don't know.

This is probably one of the least understood and noticed effects of recoil. It's there in every way, and again, even if we don't notice it, it's still moving the gun.

I don't know what it has to do with dual recoil springs either, but it is interesting and again, certainly worth mentioning.