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PSI vs Gun Recoil

Discussion in 'Uncategorized Threads' started by gjmen, Jun 29, 2007.

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  1. gjmen

    gjmen Member

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    Does the higher the advertised PSI of a load equal more recoil? ei, will a 1200fps 11/8 shell with 8200 psi have less percieved recoil than a 1200fps 11/8 shell with 9900 psi? Thanks, gjmen
     
  2. phirel

    phirel TS Member

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    Recoil is not directly related to pressure. The pressure moves the ejecta forward and this movement results in recoil. If the ejecta in two different loads are moving at the same speed and have the same weight, as in your question, the recoil would be the same regardless of pressure.

    Pat Ireland
     
  3. Gary Waalkes

    Gary Waalkes Well-Known Member

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    Right away, you want to talk about perceived recoil versus actual recoil which is a calculated number. So if we are going to ignore physics and go with how it feels, I am sure the lower PSI will produce lower perceived recoil. If you believe it, it must be true.

    If you want to talk about reality, drop your notion of perceived recoil and stay with science. Pressure is not part of the recoil formula. You want lower recoil you must increase the weight of the gun or reduce the load (shot or powder or both).
     
  4. dverna

    dverna Active Member

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    Load A 1200 fps at 9,000 PSI
    Load B 1200 fps at 11,000 PSI

    Both use the same wad, shot charge and powder weight (different powder though - obviously).

    No difference in recoil.

    Don
     
  5. Harold

    Harold TS Member

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    Free recoil energy does not tell the whole story of felt recoil. It is a good way to compare differences in projectile weight, velocity and gun weight, all other factors being held equal, and that’s about it. That being said, I very seriously doubt anybody can tell the difference between Red Dot, Green Dot and Unique, except maybe as a placebo effect.

    The reason I say that is the gun displacement involved. The difference between the fast and slow powders shows up in the peak pressure that occurs very early, maybe in the first couple of inches of shot travel down the barrel. The gun movement would be measured in hundredths of an inch, barely enough to start compressing the soft tissue of your shoulder. You are simply not feeling the recoil yet at this point in time. The only way you could be feeling that is if your gun’s butt plate is hard up against a bone, and even then, I doubt it.

    If you felt the recoil this early, a semiautomatic would not do anything to soften the recoil. A gas semiautomatic acts just like any fixed breech shotgun, until after the shot has traveled more than a foot down the barrel to where the wad passes the gas ports. Then it takes still more time for the gas to fill up the piston and accelerate the bolt rearward. This is a whole different scale of time than the Red Dot/Green Dot/ Unique pressure peaks. So if you think the semi-auto reduces recoil, you cannot logically at the same time think you already felt the recoil before the semi-auto even had a chance to cycle the action.
     
  6. Paladin

    Paladin Well-Known Member

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    If there are different rates of acceleration of ejecta, recoil has to be different. That can not be escaped! And yes, some can feel it. (I am getting away from the original subject, slightly).


    Something that probably never has been said at a trap club; I am going to use faster burning powder because it shoots softer.
     
  7. Quack Shot

    Quack Shot Active Member

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    gjmen

    Theoretically, there should be no difference between the 8200 PSI load and the 9900 PSI loads recoil, except what could be attributed to the difference in the weight of the powder. That is, provided the velocity is the same and that the same weight of shot and the same wads were used.
     
  8. Harold

    Harold TS Member

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    PerazziBigBore wrote: "no one here thinks a autoloader kicks less than a fixed breech gun.. Now do they??????? And NO ONE feels recoil after the shot has left the barrel.."

    I think the opposite is true. Most people think an autoloader kicks less. And why do you say no one feels recoil after the shot has left the barrel? The gun is still moving after the shot has left the barrel and will slam into your shoulder at some point in time. See discussion below.

    Paladin wrote:

    "If there are different rates of acceleration of ejecta, recoil has to be different. That can not be escaped! And yes, some can feel it."

    No, it doesn't have to be different. Let's put some numbers to what I wrote above. Let's say your gun weighs 100 times as much as the shot charge. (100 times 1 1/8 oz divided by 16 ounces per lb = 7.28 lb.) and the barrel is 30 inches long. By conservation of momentum, the gun will move 0.3 inches in the time it takes for the shot to leave the barrel. I think we can all agree that after the shot has left the barrel, any difference in powder burning speed is long past. So if you hold your gun just 3 tenths of an inch away from your shoulder, it is physically impossible for your shoulder to detect any difference. And, I think that 3 tenths of an inch window to feel the difference is actually much less, because the pressure peaks have passed very much earlier than when the shot leaves the end of the barrel.
     
  9. phirel

    phirel TS Member

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    I am much more comfortable talking about total recoil than perceived recoil. Perceived recoil has so many variables that each shot may be perceived differently even if the exact same thing is happening.

    First, perceived recoil is felt in the brain. Nerve impulses that originate in the shoulder and cheek travel around 2M per second to the pain centers in the brain. The shot has left the barrel before these sensory impulses get to the brain so recoil is felt some time after the gun has slammed into the body and the shot has left the barrel.

    The sensitivity of the brain to these stimuli varies within one person and this sensitivity can change within a second or so. Local hormones produced by the brain can greatly reduce the perceived recoil. Additional stimuli entering the brain can also suppress the perceived recoil. If you step on a sharp tack at the same time the gun slams into your face, you will perceive mush less recoil. An aspirin 15 minutes prior to shooting will reduce perceived recoil.

    I enjoy discussions about total recoil, but the introduction of the term perceived recoil can get quickly into an unquantifiable realm.

    Pat Ireland
     
  10. mrskeet410

    mrskeet410 TS Member

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    My .410 ammo has high pressure. My .410 has little to no recoil, perceived recoil, felt recoil, calculated recoil, nor total recoil.

    My 12 gauge ammo has lower pressure. It has all those types of recoil.

    Believe it, or not.
     
  11. Neil Winston

    Neil Winston Well-Known Member

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    Sticking to actual recoil as defined as gun movement, section 4 of the above link shows that experiments indicate that gun movement is related to shot speed and totally unrelated to maximum chamber pressure.

    Neil
     
  12. bigbore613

    bigbore613 Active Member

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    Set hook, lighten drag then play at will or until prey gives up! Jeff
     
  13. shot410ga

    shot410ga Well-Known Member

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    The laws of physics say that a " action will create an equal reaction." Example: if an automobile traveling at 50 mi. an hour hits a solid block wall. The actual impact speed is 100 mi. an hour. So when one talks about recoil, are talking about foot-pounds of energy at the moment of explosion to push the shot out the barrel. Likewise; an equal amount of foot-pounds of energy is exerted to the rear of the explosion, or against your shoulder. Example; As the chamber , let's say is 1 in. in diameter, and the recall pad is let's say 4 in.², then the foot-pounds of energy from the 1 in.² chamber area would be spread over the 4 in.² in the recall pad. Assuming, 30 ft.-pounds of energy in a target load, each square inch of the recall pad would be releasing 7.5 ft.-pounds of energy against an equal area of shoulder.

    As a result, judging recoil by chamber pressure is on an inaccurate assessment. The PSI is simply telling you what the chamber pressure will be so your gun stays in one piece. Moving the mass of shot via foot-pounds of energy is the determining factor as to what the recoil will be.
     
  14. Neil Winston

    Neil Winston Well-Known Member

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    s410, I'm sorry to tell you that everything you wrote is completely wrong. Everything. That would be a new record were this not TS.com.

    Neil
     
  15. halfmile

    halfmile Well-Known Member

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    Perceived recoil: varies with the time over which it is applied to the shoulder.

    Getting hit with a 10 lb hammer once is worse than ten times with a one pound hammer provided the velocity is the same.

    If the ejecta was instantly moving at 1200 fps the recoil would probably break your shoulder. Green Dot takes longer to reach the velocity, therefore felt recoil is less.

    Autoloaders deliver recoil to the shoulder over a longer time period, so less recoil is felt. correction: less recoil is felt at any given instant.

    If you saw the scope traces from a presure sensor you would understand.

    HM
     
  16. Neil Winston

    Neil Winston Well-Known Member

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    Halfmile, I'll try to find those traces. Red Dot and Green Dot are very close to the same. Refer to Harold's post above.

    Neil
     
  17. phirel

    phirel TS Member

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    HM- The pressure traces will show a time difference of about 3/10,000 of a second (time to reach peak pressure) between Red Dot and Green Dot. The peak pressure is not directly related to recoil but is an indication of when and how fast the shot begins to move.

    Pat Ireland
     
  18. shot410ga

    shot410ga Well-Known Member

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    I was wondering if anyone would say anything!!!!
     
  19. Gary Waalkes

    Gary Waalkes Well-Known Member

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    Please tell me what physics course you have taken that explains all of this BS. Oh gee - a physical phenomenon that cannot be explained with physics. How can that be? If you have a physical phenom that cannot be explained with an equation, or you cannot write an equation for it, it is just bs. Forget recoil, I think you all have percieved reality.
     
  20. Gary Waalkes

    Gary Waalkes Well-Known Member

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    Mike, you and I both know that a heavy gun and light loads will have less recoil than a light gun shooting silver bullets. But telling me that if I put some equivalent loads together, except one is red dot and one is green dot and the shooter will be able to tell the difference, I have a problem with that. The only percieved recoil phenom I have experienced are directly related to a gun that needs fiting.

    With a well fitted gun, I can easily discern the difference between 1oz and 1 1/8 oz loads. I can easily discern the difference between 1250 fps shells and 1145 fps shells. I honestly cannot tell the diff between green dot and red dot loaded shells.

    You are asking me for the equation. I was asking those of you who think there is a difference beyond gun weight and load to provide the math that you are using to determine this indeterminate recoil reduction that you all seem to believe in.

    Perhaps my post was a bit strong, but please, if you are going to claim recoil reduction you should be able to back it up with an equation. And the fact is that you cannot. There is no equation for "percieved" or "moment" or anything else being touted here. Sorry, you guys are just being silly.
     
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