Is excess powder really blown out?

[Britsmoothy]

Is there a correlation between increased velocity and increased accuracy as you increase the powder load?

I believe there is but for a host of reasons! And I have no scientific evidence for my belief.

 

[Carbon 6]

I have no scientific evidence for my belief.

Want some ?

 

[Zonie]

Is there a correlation between increased velocity and increased accuracy as you increase the powder load?

There can be but there may also be a correlation between increased velocity and decreased accuracy.
I guess that pretty much rules out the word "correlation".

When it comes to accuracy, each individual gun will have one or two powder loads that seem to work best.
Because of this, if one is starting their accuracy tests with small powder loads they will see the accuracy get better with increased load sizes up to a point. Then, further increases will often cause the group size to increase or worsen.

Some guns never get better as the load size is increased further. Others may start showing worse accuracy with the increased powder load and then as the load is increased more they will start shooting more accuretly again. Sort of a, "poor>better>better>better>best>worse>worse >better>better>best" situation.
Which one of the "bests" is actually best can't be predicted.

 

[Darrin McDonal]

The only possible way you could have unburned powder coming out the end of a barrel is if you filled that barrel to the very muzzle. Your normal powder charge Burns within the first two or so inches from the breech. What's coming out the end is glowing embers of powder residue. Less than 50% of the powder is actually burned as propellant the rest is fouling.

 

[Grenadier1758]

There is a correlation to a point. There are velocity nodes where accuracy peaks. After optimal accuracy is reached, increased velocity will open the groups.

 

[Spike]

to Beaver trapper, No. with a 45 cal I found the best accuracy around 70 gr

 

[Artificer]

Is there a correlation between increased velocity and increased accuracy as you increase the powder load?

Good question! The answer is, "Yes, BUT only up to a certain point where the group size then begins to open up to a larger group size when you add more powder for more velocity." The point where you reach the smallest group size, when adding powder to increase velocity, is going to be at least a bit different between gun to gun and even when the guns are otherwise very similar. It all depends on caliber, type and granulation of the powder, twist of rifling and the length of the barrel.

For example in my own hand built .45 cal. flintlock rifle with a Douglas "1 in 48 twist," 39 inch long barrel. My "target load" where it shot the smallest group size for shooting paper or other targets at 25 and 50 yards was 42 1/2 grains of Dupont FFFg. However, I didn't feel that was enough velocity for deer size game.

Increasing the powder charge beginning at 50 grains of FFFg Dupont powder saw the group size at first get larger and then around 60 grains accuracy/group size got smaller as the powder charge was increased every 5 or 10 grain increase until it shot the best group size at 80 grains of FFFg (though not quite as small as the 42 1/2 grain target load). Increasing the powder charge just another 5 grains more from 80 and the groups got larger with every increase, until I stopped at 100 grains. Since 80 grains of FFFg was plenty for deer size game and it shot the smallest group size at that powder charge, that became my hunting load for that rifle.

Gus

 

[Grenadier1758]

Is there a correlation between increased velocity and increased accuracy as you increase the powder load?

So far at least three of us (Zonie, Artificer and me) and Dutch Schoultz have identified a correlation between accuracy and the variation in accuracy due to changes in velocity.

Once optimal accuracy for the purpose is identified, be it for target or hunting, and that level of accuracy is repeatable, the why care if unburned powder is being shot along with the ball?

 

[bisleyjohn]

If I may, I'll shove in my English two penny-worth?
All calibres and projectile weights, both nitro (excuse the language) and black have an optimum velocity. This is usually (but not always) found at the upper half of the recommended powder loads. Newly acquired firearms should be extensively tested by the shooter to determine best bullet/powder load etc.

When I worked for the NRAUK, we had a new Chief Executive who, to put it politely, couldn’t tell his butt from his muzzle. He fretted over unburnt powder after someone mentioned it.

The National Rife Association of the United Kingdom not only paid me to carry out extensive tests, witness screens, white card to catch residue, photographs etc. for unburnt powder, they provided the ammunition. I had a great two days free shooting. We used the finger and flame method of testing the ‘ash’ produced by the ignition.

I have no documentary proof, it belongs to the NRA. But I can categorically state that I found no unburnt powder regardless of powder weight, even firing wadding only; it all goes up in smoke. (and smies)

 

[Artificer]

So far at least three of us (Zonie, Artificer and me) and Dutch Schoultz have identified a correlation between accuracy and the variation in accuracy due to changes in velocity.

Once optimal accuracy for the purpose is identified, be it for target or hunting, and that level of accuracy is repeatable, the why care if unburned powder is being shot along with the ball?

The theory on why accuracy changes as you increase powder charges is due to the changes of the pressure waves in the barrel at the different powder charges. The best group sizes come when the projectile leaves the muzzle of the gun at either the top or bottom of a pressure wave.

Powder charges that send the projectile out of the muzzle between the tops or bottoms of the pressure waves is why the groups open up or get smaller as the powder charge is increased - until you hit the "sweet spots" at the tops or bottoms of the pressure waves. In the case of my rifle I mentioned above, the "sweet spots" or where the powder charges caused the projectile to leave the muzzle at the top or bottom of the pressure wave was at 42 1/2 and then at 80 grains.

Gus

 

[Artificer]

If I may, I'll shove in my English two penny-worth?
All calibres and projectile weights, both nitro (excuse the language) and black have an optimum velocity. This is usually (but not always) found at the upper half of the recommended powder loads. Newly acquired firearms should be extensively tested by the shooter to determine best bullet/powder load etc.

When I worked for the NRAUK, we had a new Chief Executive who, to put it politely, couldn’t tell his butt from his muzzle. He fretted over unburnt powder after someone mentioned it.

The National Rife Association of the United Kingdom not only paid me to carry out extensive tests, witness screens, white card to catch residue, photographs etc. for unburnt powder, they provided the ammunition. I had a great two days free shooting. We used the finger and flame method of testing the ‘ash’ produced by the ignition.

I have no documentary proof, it belongs to the NRA. But I can categorically state that I found no unburnt powder regardless of powder weight, even firing wadding only; it all goes up in smoke. (and smies)

John,

I got a real kick out of this post. Thank you!

Over 200 years since the Royal Society of London proved all powder was burnt in the bore near the breech (from tests done by them in 1743 and 1751) and someone there still didn't believe it, either.

Gus

 

[bisleyjohn]

Thanks Gus,

The other way would have been to direct my boss to the NRA library, but I'm old and daft not old and stupid

 

[Artificer]

Thanks Gus,

The other way would have been to direct my boss to the NRA library, but I'm old and daft not old and stupid

Yes, if the Boss won't do his own homework, then he deserves to pay someone else to do it for him.

Gus

 

[Black Hand]

Yes, if the Boss won't do his own homework, then he deserves to pay someone else to do it for him.

Gus

The biggest problem is these bosses get paid so much more for being complete idiots and taking credit for the work of others...

 

[garryd]

Spike, would you be willing to share the chronograph data? Would like to know calibre, powder granulation, grains of powder, barrel length, weight of bullet and velocity. Intend is to correlate average barrel pressure to velocity. Thanks.

 

[Carbon 6]

I have chronographed loads up to 150 grains and the velocity keeps increasing. Also the recoil

Is the velocity gain linear ? I think the argument that folks have been making is that it isn't.

Is there a direct correlation between recoil and velocity ?

What causes recoil ?

What was your test firearm ?

What distance was the chronograph from the muzzle ?

 

[M. De Land]

Yes, if the Boss won't do his own homework, then he deserves to pay someone else to do it for him.

Gus

I think is was the experimental ballistic work of Dr. Mann if memory serves, that tackled the question of how far up bore black powder was completely consumed in a rifle barrel and I think he found that it required several inches for the front of the column to ignite. It did not all burn instantly at ignition as some had thought. I'm going by memory and will need to dig up his work and read it again.
I found his book was written in 1909 and don't have a copy of it but I thought it concerned black powder ignition but may be mistaken that it might have been early semi-smokeless he was experimenting with.

 

[RAEDWALD]

Greener, amongst others, tried cutting a barrel back until deflagration left unburned powder. He got to 2 inches beyond the charge IIRC before finding unburned powder. What he did find was that the velocity decreased. Despite the powder all burning early velocity does increase (up to a point) as barrel length increases nevertheless. We pay too little attention to the adiabatic expansion of the gases. A considerable part of the expansion comes not from the production of gases but from their expansion as it heats. This is one reason why Aubonne Swiss sporting powder uses slightly more saltpetre than is the normal optimum. Not to make more gas but to heat the gas further.

I see accuracy and barrel length has drifted into the thread. Leaving aside sight radius. For which older eyes need less as they work better with the rear sight further away from the eyes even if it shortens the sight radius. Your barrel bends like a spring when you fire. How much varies with the type but changing the charge produces a different harmony to the spring so the barrel points slightly differently as the bullet/ball leaves the muzzle. Doubters need only look up slow motion shots of an unmentionable AK on youtube to see the barrel visibly flex wildly. Thus different loads have different points of impact from this cause as well as from the change in velocity. They can work such that a greater charge with a higher velocity will result in a lower POI instead of a higher one as it catches the barrel flex at a different, lower point in the cycle. The muzzle of a thin modern unmentionable barrel can cycle through (exceptionally) a whole half inch of movement. A military musket probably moves least of all bar heavy target rifle barrels.

 

[bisleyjohn]

Internal Ballistics. There is a library of books out there, I have a couple here. Father Frog has an interesting page on the subject: https://www.frfrogspad.com/intballi.htm

Years ago I studied positively and negatively compensated barrels, effects of different vibrations casused by seer trip, hammer/firing pin strike etc. etc.

Then I went out and tried different loads to positively compensate the negative compensations. That was positively more fun

Now then, back to unburnt powder.....

And a cup of tea

 

[robinghewitt]

Is there a direct correlation between recoil and velocity ?

The achemist Newton tells us that every action has an equal and opposite reaction.

My Baker rifle weighs 7 lbs and fires a 20 gauge ball. I multiply 7 by 20 and find the gun weighs 140 times the weight of the ball. Weighing balls by gauge makes this so easy.

The ball travels 28" and exits at around 1050 ft/s.

To find out what the gun does I simply divide by 140...

The gun moves 28/140 = 0.2" and accelerates to 1050/140 = 7.5 ft/s, approx 5 mph

Isaac Newton was one smart cookie back in 1687