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recoil gizmo physics

Discussion in 'Shooting Related Threads' started by Johnny, Sep 21, 2011.

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  1. Johnny

    Johnny Well-Known Member

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    How does a Dead Mule and mercury reducers actually work?
     
  2. skeet_man

    skeet_man Well-Known Member

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    Added weight.
     
  3. Recoil Sissy

    Recoil Sissy Well-Known Member

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    Added mass is part of it.

    The mechanisms of semi-autos are another form of recoil reduction gizmo. There is no 'added' mass but all that steel (bolts and other moving parts) thrashing about spread part of the recoil impulse over time thus reducing felt recoil.

    I've never used a Dead Mule but mercury (for example, C & H) and other reducers do indeed help with perceived recoil.

    sissy
     
  4. Johnny

    Johnny Well-Known Member

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    Sissy, specifically, how does a mercury reducer work?
     
  5. Hap MecTweaks

    Hap MecTweaks Well-Known Member

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    Johnny, being liquid, it must splash forward at firing to slam into the front of the housing to get the full benefit of it's weight.

    A solid mass of weight works faster on reducing felt recoil. Faster than spring loaded models, liquid or any that must slide into a stop! Any added weight works, some just work a tad quicker than others.

    Hap
     
  6. Recoil Sissy

    Recoil Sissy Well-Known Member

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    johnny:

    Newton's first law of motion (sometimes called the 'law of inertia') says in part: An object at rest will remain at rest unless acted on by an unbalanced force.

    Your gun is the object at rest. A fired shotshell creates the unbalanced force (recoil) that overcomes inertia and puts the gun in motion.

    The more mass an object has, the more force it takes to move it. That's why most target guns are intentionally made relatively heavy. By adding more mass you increase the inertia required to make it move thus reducing felt recoil.

    Mercury is a material of choice for reducers because it is really dense and as Hap pointed out - liquid. You can get the same general effect by:

    1. putting a partially filled tube of lead shot in your stock or taping it to your barrel. Or...

    2. putting solid chunk of lead in your stock or on your barrel.

    Make sense??

    sissy
     
  7. Gapper

    Gapper TS Member

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    Some of the mercury filled type have a baffle built in to move the gun stock away from your face upon recoil. This differentiates them from solid metal. They require proper orientation in your stock.

    I've never cut one open to see how it works, but I can imagine how it could help recoil.

    I took mine out, for better balance. GAP
     
  8. Shooter R

    Shooter R Active Member

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    Adding dead weight WILL lessen recoil. It probably dosen't matter if it's a "recoil device", or just added weight to the gun. Added weight WILL affect how the gun moves however. Stock weight = quicker, Barrell weight = slower.

    But "The question you have to ask yourself" (a quote form Clint Eastwood) is... does the recoil hit you in the shoulder, or in the face. I've never understood it when shooters tell me it "HITS" them in the shoulder. I guess that's just me, as that never seemed to be a problem.

    However... when they say it hits them in the face, I know what they mean. This is probably an issue of gun fit. I solved it with a PFS. That worked fine with the Perazzi I used to shoot. It seems the "springy" type external stock based recoil devices (PFS, and "springy things" before the recoil pad, etc.) do spread out the "JAB", and do let you STAY in the gun for a better score.

    You can manage recoil. It shoud not keep you from attaining your best scores.

    It's been my experience that if you reload, you should REALLY try some loads that are a bit on the light side. You may be surprised at how "low you can go".
     
  9. whiz white

    whiz white Strong Supporter of Trapshooting Banned

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    The physics of it? It's all F=ma<BR>
    "Force" (felt recoil in this case) = "mass" x "acceleration." Slow down acceleration and you have less felt recoil.

    Consequently, 99.99% of a recoil reducer's solution is simply WEIGHT.

    You'd be better off simply pouring in some shot in the butt-stock. Pour some shot in a sock and then drop it - I bet it won't bounce. Its mass is so great and since each pebble is unto itself, the bounce, or recoil effect, is literally gone.

    Here's a photo done a couple of years ago that I put up on this site in regard to some of the various brands of reducers.


    moderator_2008_030342.jpg
     
  10. Johnny

    Johnny Well-Known Member

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    My question does not concern "dead weight", that is easy to understand. I'm having trouble understanding how mercury can actually reduce the recoil. The mercury is at rest at the moment the gun fires. It is going to resist movement initially. As the gun recoils the mercury has to move forward and slam into the end of it's container to have any reducing effect. I think the recoil event is going to be over before the mercury can have a chance to make any difference at all. Essentially, I thing the mercury would have to be shot forward by a separate force to have an effect.
     
  11. Hemlock

    Hemlock Member

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    I believe you’re looking at the way a mercury recoil reducer works, the wrong way.

    The mercury, which is one of or the heaviest liquid, actually stays put or doesn’t move when a gun is fired. Instead the container around it moves rearward and hits against the mercury “glob” thus damping the recoil of the gun moving rearward.

    I would think a spring mechanism would work the same way. That’s why one like the Dead Mule has to be installed with the correct end toward the muzzle.

    Later, Ken
     
  12. whiz white

    whiz white Strong Supporter of Trapshooting Banned

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    I guess you didn't get the jest of my post.

    They DON'T work, EXCEPT as added mass.
     
  13. halfmile

    halfmile Well-Known Member

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    The baffle in the mercury reducer serves to infinitesimally spread out the time of the infinitesimal amount of recoil it soaks up, resulting in an infinitesimal decrease in perception of recoil accompanied by a moderate decrease in wallet.

    HM
     
  14. Hap MecTweaks

    Hap MecTweaks Well-Known Member

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    By the time everything happens with liquids and springie thingies, the gun has already kicked you?

    Hap
     
  15. Johnny

    Johnny Well-Known Member

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    I was hoping to lure out some of the crazy explanations like I get at the gun clubs, which usually includes some gesticulation.
     
  16. timb99

    timb99 Well-Known Member

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    Well, there are a number of things we can do to reduce or mitigate recoil.

    Simplistically, just adding weight to your gun is one of them.

    But think about a WWII era wheeled trailer-type howitzer pulled by a truck. They have springs and damping cylinders on those things to counteract the recoil of the gun, otherwise the blast from the gun would move the entire thing back 30 feet.

    Then you have the various designs such as PFS and Bump-Buster and RAD, etc. These things work quite well, and they work kind of like the howitzer mechanism.

    Then you have something like a Browning Recoilless, where you are actually moving a large mass forward before the shell is fired to counteract the recoil. It works! I've shot one, and there is NO recoil.

    Then you have gas-operated shotguns like the 1100 that moves a substantial weight (the bolt and action sleeve) while the recoil event is taking place, that effectively damps the recoil. Doesn't eliminate it completely.

    That said, these devices you asked about aren't completely useless, its just that their inner workings weigh too little to make them very effective at damping recoil. They DO add overall weight to the gun, which IS effective. But the mechanisms might just as well be solid.
     
  17. AveragEd

    AveragEd Well-Known Member

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    Put me in the column under "thinks they help." I have arthritis in most of my joints and while recoil ON my shoulder doesn't bother me a lot, I can feel its effects IN my shoulder the next day, so I'm sensitive to how much a long gun kicks me. I have a Dead Mule attached to an 870 magazine cap and by quickly switching from a bare cap to this one makes a difference you can feel. By the same token, I also have a weighted magazine cap that's actually heavier than the one with the Dead Mule and can't feel much if any difference with it installed.

    Beretta makes a "Recoil Reduction System" that is for all intents and purposes a larger Dead Mule. It is intended for use in one of their autoloaders but they can be fit into a 680-series stock and I put one in my 687 combo's stock. I can feel a difference but someone told me that I think it works because I can hear its slight clicking noise, so I handed my gun to a 682 shooter one time and asked him to shoot it for a post and tell me if he noticed anything different. He was a lefty and my stock not only is right-handed but has been bent and the comb is moved to the right, all of which made the gun not fit him about as much as a gun can not fit someone. When he handed the gun back to me, he said, "Yours kicks less than mine."

    However, I can't say I've been able to tell any difference with or without a mercury reducer installed.

    Below are two photos for an article I wrote about some of the recoil reduction methods I've tried.


    averaged_2008_0303257.jpg

    averaged_2008_0303258.jpg


    The two gray tubular devices are mercury reducers and the small object is a piece of Mallory Metal, a material that is seven times more dense than lead that I use to add weight in small places. The second photo is of the two magazine caps I mentioned.

    Ed
     
  18. whiz white

    whiz white Strong Supporter of Trapshooting Banned

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    HalfMile said it best: "... a moderate decrease in wallet."

    Since we're really talking about weight, but I agree about the howitzers... except we're not using hydraulic dampening devices here, consider the following:

    Specific Gravity of Lead (Pd) is about 11,340 kg/m^3, and<BR>
    Specific Gravity of Mercury (Hg) is about 13,593 kg/m^3

    Because Mercury is relatively expensive, and because a trapshooter nearly always has Lead available, use it.

    I have a drawing (need to finish it) showing why the Mercury reducer does not work due to its position in the butt-stock. However, speaking of hydraulics, the BearTrap is one that uses oil in its design to act as a hydraulic buffer to slow the action of the lead cylinder inside it.

    I have take a BearTrap and dropped it carefully to have it actually never bounce and it will stand straight up. That tells me that it has some dampening effect since there is no bounce. No bounce means it has absorbed some of the fall's gravitational effects. An Edwards will bounce, and so will most others.

    IMHO.

    WW
     
  19. skeeljc

    skeeljc Supporting Vendor Supporting Vendor

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    The spring, hydraulic, air type recoil devices work better than just adding mass to your gun. The reason is they actually reduce the peak acceleration by spreading it out over a longer time interval. There must be some displacement or movement between the gun and the but plate to accomplish this. A recoil pad allows the gun to move relative to your shoulder. A recoil device like a R.A.D., Gracoil, G-Squared allow the gun to move more than a recoil pad so they do a better job of spreading the recoil over a longer time period.

    Jim Skeel
     
  20. timb99

    timb99 Well-Known Member

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    Ed,

    Just fyi;

    Mallory Metal = mostly tungsten (wolfram)

    Dense stuff, but not remotely 7 times more dense than lead.

    From their website, Specific Gravity of the various Mallory Metal types is from 16.7 to 18.1 g/cm^3

    Which is about 1.6 times more dense than lead.
     
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