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Thread: Muzzle energy of shotgun loads

  1. #1
    Boolit Mold
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    Question Muzzle energy of shotgun loads

    How do you calculate the relative muzzle energy (or felt recoil) of various shotgun loads using load weight and muzzle velocity?

  2. #2
    Boolit Master
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    (projectile weight in grains x muzzle velocity (f/s) x muzzle velocity (f/s)) divided by 450240
    Last edited by Kosh75287; 10-19-2022 at 09:14 PM. Reason: math notation deficiency
    For in much wisdom is much grief: and he that increaseth knowledge increaseth sorrow. Ecclesiastes 1:18
    He that troubleth his own house shall inherit the wind: and the fool become servant to the wise of heart. Proverbs 11:29
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  3. #3
    Boolit Buddy
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    Look up recoil calculator on line.

  4. #4
    Boolit Master
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    Quote Originally Posted by shortlegs View Post
    Look up recoil calculator on line.
    Sorry, I didn't see the f(or felt recoil) part.
    For in much wisdom is much grief: and he that increaseth knowledge increaseth sorrow. Ecclesiastes 1:18
    He that troubleth his own house shall inherit the wind: and the fool become servant to the wise of heart. Proverbs 11:29
    ...Verily I say unto you, Inasmuch as ye have done it unto one of the least of my brethren, ye have done it unto me. Matthew 25:40


    Carpe SCOTCH!

  5. #5
    Boolit Buddy
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    That would be the recoil energy. ShootersCalculator.com

  6. #6
    Boolit Master
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    Is the wadding a significant part of the calculation? As to what is 'felt', the weight of the shotgun should be included in order to calculate the velocity of the recoil that is needed.

  7. #7
    Boolit Grand Master


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    Quote Originally Posted by barnetmill View Post
    Is the wadding a significant part of the calculation? As to what is 'felt', the weight of the shotgun should be included in order to calculate the velocity of the recoil that is needed.
    No. Even the heaviest wads are likely to be a steel shot wad. They are like 40 grains, some more, some less. 40 grain wad is nothing compared to 492 grains of shot.

  8. #8
    Boolit Buddy
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    Quote Originally Posted by megasupermagnum View Post
    No. Even the heaviest wads are likely to be a steel shot wad. They are like 40 grains, some more, some less. 40 grain wad is nothing compared to 492 grains of shot.
    Well, 8% or so.

  9. #9
    Boolit Master


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    Muzzle energy = 1

    Recoil energy = 2

    Which do you want?

  10. #10
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    W.R.Buchanan's Avatar
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    The recoil energy is what it is. The actual relative power of the load is best expressed by TKO IMHO> TKO or Taylor Knockout Value is arrived at by using the following formula.

    Diameter of Bullet/Slug x Weight in Grains x Velocity / 7000. This will yield a 2 or 3 digit number than can then be compared to other cartridges.

    Example: a 12 ga. 1 oz. Slug at 1600 fps= TKO 72.9,,, Compared to a .458 Win Mag 500 gr Bullet at 2150 fps .458 x 500 x 2150= TKO 70.3

    So a 12 ga Shotgun with a high base slug is very close to a .458 Win Mag. But the difference is how the energy is transferred to the target. The Slug due to it's larger diameter, Transfers most of its energy instantaneously to the target. The Frontal Area of the Rifle Bullet is only 1/3 of the Frontal Area of the Slug (.164 Sq in versus .418 Sq in.) so it becomes obvious which one will transfer its energy more efficiently. (VW vs Bus analogy) The rifle bullet will penetrate further than the slug which in some cases is more desirable or it will go all the way thru the target and end up expending its energy into the ground beyond. Application determines which is better for you.

    The recoil energy of this is the back side of the equation. Brenneke makes a 1 1/2 oz. Slug that runs 1600 fps! It is suitable for hunting T Rex! The TKO on that load is 109! And touching one off in a 7 lb. shotgun would be a life altering experience !

    Randy
    "It's not how well you do what you know how to do,,,It's how well you do what you DON'T know how to do!"
    www.buchananprecisionmachine.com

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Abbreviations used in Reloading

BP Bronze Point IMR Improved Military Rifle PTD Pointed
BR Bench Rest M Magnum RN Round Nose
BT Boat Tail PL Power-Lokt SP Soft Point
C Compressed Charge PR Primer SPCL Soft Point "Core-Lokt"
HP Hollow Point PSPCL Pointed Soft Point "Core Lokt" C.O.L. Cartridge Overall Length
PSP Pointed Soft Point Spz Spitzer Point SBT Spitzer Boat Tail
LRN Lead Round Nose LWC Lead Wad Cutter LSWC Lead Semi Wad Cutter
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