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Fast vs Slow


Wheeljack

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16 minutes ago, IDescribe said:

 

Higher pressure means more gas is being pushed faster, but it's still not the pressure that increases the recoil, it's the energy of the moving mass of gas.  It's no different than the recoil created by the bullet, except that one is a mass of gas, and the other is mass of metal.  If you had a metal container strong enough to contain the pressure of some powder charge without stretching, and you held the container while the powder was ignited, you wouldn't feel it press against your hand at all, despite the rapid increase in pressure internally.  Pressure doesn't recoil.  It's the energy of the moving masses that creates recoil, and yes, that's Newton's Third.

 

And the energy of the moving mass of gas is determined by the pressure. We are saying the same thing. I was just taking issue with you leaving that out of "Recoil energy is the reciprocal of that bullet's energy (every action has an equal and opposite reaction), mitigated by the mass of the gun as a whole, plus the movement and mass of the slide additionally, the movement of which spreads the recoil over time."

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2 hours ago, IDescribe said:


...unless the same or similar, and the resulting gas mass from one smokeless powder to the next is quite similar by powder weight.  You're not going to find two powders where one takes 3.0gr and the other takes 3.5 to move the same bullet to the same velocity in the same pistol AND the two loads recoil the same.  The 3.5gr charge will always have more gas mass and will always recoil more, despite reaching a lower peak pressure.

 

No. There's NO reason to assume that the 3.5gr charge will always have more gas mass. The oxidation/nitration is going to be different.

Edited by Wesquire
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I'm not assuming.

 

Okay, I'm going to convert grains to milligrams here so that I can talk in terms of mass instead of weight so that no one tries to pin me down on how what I say technically breaks down under different gravity.  3.0 grains is roughly 194 milligrams.  3.5 grains is roughly 227 milligrams.

 

Wesquire, if you put 227mg of powder into a cartridge, that 227mg gets blown down the barrel, mostly as gas, and with virtually no loss of mass, and by virtually no loss of mass I mean so negligibly tiny that you couldn't measure it. There is no measurable mass loss.  227mg of powder in, 227mg out.  194mg in, 194mg out.  You could make the argument that it's not all gas mass, that instead it is the mass of gas plus some mass of the solids suspended in the gas stream,  and that's technically correct, but since that makes zero difference in how much mass is traveling down the barrel behind the bullet or how the moving mass(es) create recoil, that would be a semantic argument.  

I can assure you that the mass (and weight if you'll allow me we're comparing data on the same planet) of the powder charge translates directly to the gas mass shot down the barrel. There are no two powders where 3.5 grain of powder are going to produce less gas mass (so long as we include the suspended solids) than 3.0 grains.  That doesn't exist.  Atoms in = atoms out. Powder mass translates neatly to gas mass.  

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2 hours ago, IDescribe said:

I'm not assuming.

 

Okay, I'm going to convert grains to milligrams here so that I can talk in terms of mass instead of weight so that no one tries to pin me down on how what I say technically breaks down under different gravity.  3.0 grains is roughly 194 milligrams.  3.5 grains is roughly 227 milligrams.

 

Wesquire, if you put 227mg of powder into a cartridge, that 227mg gets blown down the barrel, mostly as gas, and with virtually no loss of mass, and by virtually no loss of mass I mean so negligibly tiny that you couldn't measure it. There is no measurable mass loss.  227mg of powder in, 227mg out.  194mg in, 194mg out.  You could make the argument that it's not all gas mass, that instead it is the mass of gas plus some mass of the solids suspended in the gas stream,  and that's technically correct, but since that makes zero difference in how much mass is traveling down the barrel behind the bullet or how the moving mass(es) create recoil, that would be a semantic argument.  

I can assure you that the mass (and weight if you'll allow me we're comparing data on the same planet) of the powder charge translates directly to the gas mass shot down the barrel. There are no two powders where 3.5 grain of powder are going to produce less gas mass (so long as we include the suspended solids) than 3.0 grains.  That doesn't exist.  Atoms in = atoms out. Powder mass translates neatly to gas mass.  

 

IDK why you think the difference in powder weight is relevant. The difference in 227mg and 194mg is completely negligible. Most bullets are going to differ by more than that round to round. The relevant difference is how much and when oxidation/nitration occurs. Some powders are more nitrated than others, causing more gas from the same amount of cellulose/glycerin. That's where the pressure comes from, more gas is added to the system. You are completely ignoring the chemical reactions at play. Again, your analysis only works if you are talking about 2 different quantities of the same powder.

 

If you were correct about powder mass = gas at the same rate for all powders, then all powders would do the same thing. This is obviously not the case.

 

Let's make this simple:

 

 A mole of carbon produces the same volume when oxidized as a mole of hydrogen, but a mole of carbon is 14 times heavier. This means that a powder that oxidizes only carbon will require 14 times the weight of powder as one that oxidizes only hydrogen, but they will be producing the same volume of gas. So we know that how and what a powder oxidizes/nitrates will significantly change the powder weight -> gas equation. 

Edited by Wesquire
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Come on guys.  You drive me crazy. :(   I'm going for a faster powder, well, say medium range.  I don't like too much snap.  BULLET:  lead, coated, plated or jacketed????    Then you can get back to Newton.  :bow:

Edited by Wheeljack
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27 minutes ago, truborshooter said:

 

Explains recoil only in terms of momentum, then gives recoil numbers in units of energy. One of the problems going on with this discussion as well. Recoil can't be explained just by doing a momentum calculation. Recoil is more often, and more correctly described by kinetic energy calculations.

 

This article also ignores the fact that faster powders will have slower gas speed than slower powders.

Edited by Wesquire
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