4F Black Powder Question

VADSLRAM said:

Nothing published just my own observations and deductive reasoning. If the pressure starts to reduce before the projectile leaves the barrel then drag takes over, slowing the projectile and losing velocity will effect accuracy. So then say you just increase the load to keep the velocity up, then you will get a larger volume pushing out behind the projectile after it leaves the barrel. Fluid dynamics proves that those gasses will expand in a swirl pattern behind, around and in front of the projectile since they have less mass. That effects the accuracy just like a cross wind would except in a random pattern, not the easily compensated wind-age calculations.
Most of my observations come from Pyro work. Watching a 3 or 4 inch festival ball coming out of the tube in slow motion you can definitely see the wobble created by the "puff" after the ball leaves the tube. Bullets are smaller and more dense, but that just means the effects are less not eliminated.

Bottom line 4f isn't the best for targeting with a .50cal long gun... but if it's all you got... It still goes bang and with a little extra luck it will still put meat on the table.

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azmntman said:

We need the popcorn emoji back

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Zonie said:

Interestingly, the Bevel Brothers in a very recent issue of MuzzleBlasts magazine had an article about air spaces between the powder and ball or bullet causing a bulged barrel.
After a lot of testing with several different barrels including a thin walled smoothbore they came to the conclusion that the idea that having an air space between the powder charge and the bullet or ball was total bunk.

They intentionally loaded and fired hundreds of shots with large air spaces between the powder and projectile. Most of them duplicated what would happen if the shooter left the projectile 2 to 3 inches from the muzzle. This would happen if they short started the projectile and then forgot to ram it down to sit on top of the powder.
They used powder loads up to over 140 grains of powder in many of these tests.
The final result after making precision measurements of the barrels in many areas with a micrometer? Not a single barrel bulged or showed the slightest deformation with any powder load or with the projectile loaded at a number of different depths leaving different size air-spaces.

After they got tired of trying to cause a bulge in a barrel that was caused by leaving an airspace between the powder and the projectile, they changed their tactics.

They loaded a moderate powder load and then a patched ball on the powder. After doing this, they intentionally "short started" another patched ball, leaving it a few inches below the muzzle.
In these tests with two projectiles loaded and an airspace between them, they found that the barrel had indeed "bulged" at the location of the short started ball. With the smoothbore barrel, it bulged and split at the muzzle end.

The conclusion? Leaving a large air space between the powder and the projectile will not damage the barrel. The only bad thing that will happen is, the projectile will have a very low velocity.
The other part of the conclusion? Loading a muzzleloader properly and then loading another projectile, leaving a air space between it and the lower projectile will either bulge the barrel or cause it to explode.

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Britsmoothy said:

So let's get this straight.
You don't want the ball to drag itself out of a barrel but prefer positive pressure behind it because you believe it affects accuracy but you don't want to much pressure because to much pressure at the muzzle is also bad for accuracy.
You also believe this can be regulated by choice of powder granulation!

So I guess you would recomend a short barrel for 4f users and a normal or extra long barrel for larger grades of powder because then the ball in the short barrel won't have to struggle to leave the barrel from "drag" factors but the larger powder grades can overcome the "drag" because they keep pressure up all the way to the muzzle but magically don't affect the ball when leaving the barrel!

My head hurts.

Believe me, I have seen rifles shoot just as tight a group on fine grades as I have courser grades. How would explain that?
Frankly your observations are full of holes sir. You are implying that one powder will in effect slow a ball to allow it to deaccellerate but upping the charge will then produce to much gas but another choice of powder will just be right really? I doubt it very very much.

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Burn rate is important, however, when you are loading magnum vs. non-magnum rounds. Typically, a non-magnum load will use faster burning powders while a magnum cartridge will need slower burning powders. Magnum rounds need to generate greater power. Therefore, they use slower-burning powders, which creates peak pressure for a longer timeframe. Specifics will change by cartridge and bullet type, but in general a fast-burning powder is used for light bullets and low-speed pistols and shotguns. Medium-rate powders are used for magnum pistols, while high-velocity, large bore rifle cartridges will need slow powders, as they deliver the most overall power.

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Because of the long barrel and increased power demands, rifle cartridges need a powder that burns slower, completing the explosion through the entire barrel and delivering consistent pressure from start to finish. If you use fast-burning pistol powder in a rifle, it will make too much energy at the beginning, giving off high pressures in the chamber. This brings the risk of damaging the gun. Slower powders push the bullet evenly down the barrel and keep pressure down while utilizing the most energy.

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VADSLRAM said:

Given equal amounts by weight of an ideal powder and condition where the only variable is the grain size. Flame propagation is slower with the larger particles than the smaller ones. This equates to a production of gases over a longer period. This creates a constant pressure even as the chamber size increases because the projectile is going down the barrel.

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VADSLRAM said:

I'll try one more time. Maybe I'm not explaining clearly enough. After that you either accept the physics or not. No skin here.
Given equal amounts by weight of an ideal powder and condition where the only variable is the grain size. Flame propagation is slower with the larger particles than the smaller ones. This equates to a production of gases over a longer period. This creates a constant pressure even as the chamber size increases because the projectile is going down the barrel.
With smaller grains all the gasses are produced before the projectile reaches the muzzle. This creates a maximum pressure point at one chamber volume and then decreases as the projectile moves down the barrel and the chamber volume increases. There is also a very slight decrease in temperature of the gasses as they expand, further decreasing pressure. You can add more powder so that the burn time is longer (talking milliseconds) but that also means an overall higher pressure.
Today's solid forged barrels of high quality steel will probably never have an issue with anything other than insane over loading conditions using different formulas of powder / nitro powder.. But the increased pressure will cause two conditions that a correct load doesn't. First as I said the turbulence at the muzzle as the projectile clears. It will also push the limits of the lead / patching to hold the rifling. Both conditions have proven detrimental to accuracy.

Here is something from Wideners on reloading cartidges.


If you want your head to really hurt. Here is a rudimentary flame turbulence equation. τf = lt/u′, where lt is the integral scale of turbulence .


Extreme example and strictly cautioned against!!!
You could determine the total gas production of a double base nitro powder. Why wouldn't you use that in a muzzle loader??? Because under confinement the flame propagation of nitro powders is very much faster than BP and theoretically would produce all the gasses before the projectile even starts to move.. creating HIGHLY DANGEROUS over pressurization at the chamber. Regardless of the fact that total gas amount would be the same as a BP load.

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Britsmoothy said:

I don't think so.
You like many others bang on and on how it is dangerous without a shred of evidence to support your suggestions.
For years I have asked for evidence and none is forth coming. In fact more evidence of it's safe use can be found over any evidence that it is dangerous!
So until we know better I shall keep using it.

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Boston Bill said:

I watched a Mike Belliveau you tube video of him shooting his pocket pistol using 10 grains of 4ffff. He explained something about the size of the airspace around the granuals. I wish I paid more attention

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VADSLRAM said:

I'll try one more time. Maybe I'm not explaining clearly enough. After that you either accept the physics or not. No skin here.
Given equal amounts by weight of an ideal powder and condition where the only variable is the grain size. Flame propagation is slower with the larger particles than the smaller ones. This equates to a production of gases over a longer period. This creates a constant pressure even as the chamber size increases because the projectile is going down the barrel.
With smaller grains all the gasses are produced before the projectile reaches the muzzle. This creates a maximum pressure point at one chamber volume and then decreases as the projectile moves down the barrel and the chamber volume increases. There is also a very slight decrease in temperature of the gasses as they expand, further decreasing pressure. You can add more powder so that the burn time is longer (talking milliseconds) but that also means an overall higher pressure.
Today's solid forged barrels of high quality steel will probably never have an issue with anything other than insane over loading conditions using different formulas of powder / nitro powder.. But the increased pressure will cause two conditions that a correct load doesn't. First as I said the turbulence at the muzzle as the projectile clears. It will also push the limits of the lead / patching to hold the rifling. Both conditions have proven detrimental to accuracy.

Here is something from Wideners on reloading cartidges.


If you want your head to really hurt. Here is a rudimentary flame turbulence equation. τf = lt/u′, where lt is the integral scale of turbulence .


Extreme example and strictly cautioned against!!!
You could determine the total gas production of a double base nitro powder. Why wouldn't you use that in a muzzle loader??? Because under confinement the flame propagation of nitro powders is very much faster than BP and theoretically would produce all the gasses before the projectile even starts to move.. creating HIGHLY DANGEROUS over pressurization at the chamber. Regardless of the fact that total gas amount would be the same as a BP load.

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Bob McBride said:

I've been following this thread with interest as I've never considered using 4f in larger than .36 caliber stuff. That said, as long as one were to compensate, ie: not replacing 100g of 2f with 100g of 4f, for the larger pressures of the finer grain powders I can't imagine in modern barrels it would be an issue. Personally, before I settled on a 4f load, to stretch a pound of powder, I would work up from a small load to ballpark match the 4f load to my standard load's velocity with a chrono as that would be my only way to approximate pressures....

As to pressures, ISTM, the ideal grain size and load would burn itself out just at the muzzle using the lowest possible pressure to obtain the ideal velocity needs of your application.

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