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Interesting: Recoil due to powder weight.

Discussion in 'Handloading and Reloading' started by Macchina, Mar 23, 2013.

  1. Macchina

    Macchina Well-Known Member

    I'm sure many (most) of you know this, but I was reading about internal ballistics and a light bulb turned on. I often wondered why efficient cartridges, especially pistol caliber carbines, have such low recoil for the energy they deliver. One of the many reasons is a light-weight powder charge. I never thought about, but the mass of that powder is exerting a force on the breachface just like the mass of a bullet and the 24g of H110 in my .44 Mag is a heck of a lot lighter than the 70+ grains I used to less into my 300 Win Mag.
  2. danthearmyman

    danthearmyman Member

    It wouldn't be the mass of the powder. The powder burns to create a expanding gas. This expanding gas pushes on the bullet and the breach face equally. The bullet accelerates like hell because of its low mass as compared to the firearm. More powder=more gas produced.

    Newtons Law: Every action has an equal and opposite.

    If you push the bullet forward, the gas pushing has to push back against something.
  3. Macchina

    Macchina Well-Known Member

    That is originally what I thought, but all that gas weighs something (exactly as much as the powder out came from) and is traveling at near the same velocity as the bullet. Think about why a compensator works ..
  4. Haxby

    Haxby Well-Known Member

    Yep, all that powder goes out the end of the barrel. And since the powder is behind the bullet, pushing, as soon as the bullet gets out of the way, the gas exits at a faster speed than the bullet did.
  5. ljnowell

    ljnowell Well-Known Member

    Recoil difference could also be because the 300 win mag runs at 64,000 psi whereas the 44 Rem Mag runs at 36,000 psi. Big case, large volume of high pressure gas = more recoil. Note where I said large volume of higher pressure gas. That volume plays a role in it.
  6. Macchina

    Macchina Well-Known Member

    I Understand there are substantial differences between the .300 and .44. I'm only taking about powder weight.

    Take for example a rocket in outer space, very simplified: the exploding fuel exits the rocket at a velocity (a gun with no bullet), it is only the mass of that fuel being propelled away that that pushes the rocket.
  7. rhadamanthos12

    rhadamanthos12 New Member

    What happens with combustion is you end up with by products, if the combustion isn't complete which usually it isn't you don't use all the available energy, the unburned components appear as smoke,soot, etc. You can use the by products to determine how much air was used or wasted in your combustion.

    Energy in has to equal energy out, that is why muzzle energy would work better for recoil calculation, you just need to use the proper equation for it. Also it is going to be a multi dimensional calculation, granted we most likely only care about the horizontal component.
  8. Lost Sheep

    Lost Sheep Well-Known Member

    Empirical evidence rules over all theory

    Try this: Using a long barreled gun, load up with a stout charge of an energy-dense powder. Measure the velocity.

    Get a slower, heavier powder and load whatever it takes to match the Bullseye velocity with the same bullet and same gun. (The powder will certainly be 10-20 grains more)

    Compare the felt recoil. Compare the actual recoil.

    You would expect the heavier charge of powder to give more recoil. But I am given to understand that the lighter powder charge will FEEL heavier in recoil.

    Some say it has to do with the fact that the peak pressure of the faster, lighter powder charge is greater. Some say it has to do with the fact that the slower powder delivers its acceleration to the bullet over a longer period of time.

    I will leave it to each of you to judge for yourselves.

    Lost Sheep
  9. Haxby

    Haxby Well-Known Member

    The online recoil calculators work well to calculate recoil.
  10. kingmt

    kingmt Well-Known Member

    Lost Sheep
    Problem with that theory is the slower powder reduced to the same speed probably won't burn fully. Unless you just mean the difference between Red Dot & Blue Dot. There isn't really much difference in the recoil of those two in a rifle.
  11. Lost Sheep

    Lost Sheep Well-Known Member

    I don't understand the problem.

    The bullet winds up downrange at the same velocity.

    The powder, whether burnt, unburnt or in-process ejects from the muzzle. We are not talking about cartridge efficiency, but only about recoil.

    I don't understand your question. PM if the point is off-topic and the answer is too long to post.

    Lost Sheep
  12. Macchina

    Macchina Well-Known Member

    100% of the mass of the powder (in the form of gas) exits the muzzle at the velocity of the bullet. How could the mass of the powder contribute anything less to recoil than the bullet itself does.

    My original point was:
    .44 Mag with a 200 grain bullet + 24g of powder = 224g exiting the muzzle.
    .300 Win Mag with a 200 grain bullet + 74g of powder = 274g exiting the muzzle.

    The 300 has a 22% higher load mass, all of which is seen completely in recoil. I understand that the mass CONTRIBUTED to a much higher velocity, but in the end two 200 grain bullets are still exiting the muzzle.

    Perhaps a better example is a 357 Mag with 2 different powder charges of 6 and 16 grains, both of which deliver the same velocity with the same 158gr bullet. The 16 grain load will have a higher felt recoil with no terminal advantage.
  13. bds

    bds Well-Known Member

    It's simple application of physics (Newton's second law of motion) where force (F) is expressed as:
    It doesn't matter whether it's pistol/carbine/rifle cartridge, greater the force the bullet exerts on the breechface from expanding high pressure gas, more the recoil.
  14. rhadamanthos12

    rhadamanthos12 New Member

    I don't think you can count it that way, the powder is a potential energy. Upon ignition it become kinetic energy, if there was another force acting on the powder and the powder was not acting as a source of work on the bullet then you might be able to include it into your recoil calculation
  15. ljnowell

    ljnowell Well-Known Member

    100% of the powder will never make it out of the barrel, a large majority yes, but not 100%. Further, to illustrate the point that pressure is the commanding factor, lets take a 44 mag load with a 240g bullet and 22g of powder. Leave the same amount of powder in it and put a 300g bullet on top of it, now what happens to recoil? Or a 340g bullet?
  16. rcmodel

    rcmodel Member in memoriam

    Or use this recoil calculator.


    Notice the powder weight is part of the 'ejecta' used to figure recoil.

    All the powder gas mass isn't used as 'Ejecta" in the recoial formula because some of it stays in the barrel pushing the other way and not all of it is ejecta.

  17. Walkalong

    Walkalong Moderator

    Yep, powder weight figures into recoil. The weight gets pushed forward just like the bullet. It isn't a big part of the equation, but it is a part.
  18. jstein650

    jstein650 Well-Known Member

    The mass of powder in used in any cartridge most certainly contributes to real free recoil energy, whether it's completely consumed in combustion or not. In fact, the factor used in most calculations, the velocity of the powder gases (part of the ejecta) is multiplied from 1.25 for long shotguns to 1.75 for high powered rifles which definitely contributes to recoil, since a lot of that mass is moving faster than the bullet or shot.
    Last edited: Mar 23, 2013
  19. .22-5-40

    .22-5-40 Well-Known Member

    Most 12GA. shell boxes are printed..3 Dram Equlivant..this means the smokeless powder charge, even though of much lighter weight gives the equal velocity to shot charge as the old 3 Drams of black powder...And from what I have heard..the old timers agree the black powder loaded shells kicked harder than smokeless.
  20. kingmt

    kingmt Well-Known Member

    Actually I think I'm pulling out of this one. I didn't really understand the OP anyhow.

    As for unburnt powder tho it is wasted because it never burnt to release it's energy. I always welcome PMs.

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