# Black powder barrel length



## borderghost

Can anyone shed some light on barrel length , I am having a gun made and want to have it as short as possible , going to use it as a walking / stalking gun , Not likely be shooting over 100yards , and want to use bout 100 gr of loose powder, can a 22inch burn this amount of powder. thx


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## barebackjack

Depends on the powder.

I highly doubt real black powder will burn all of a 100 grain charge in 22 inches. And if it aint burning in the barrel, its waste.

Some of the subs may. I doubt pyrodex will, but triple 7 or one of the "new" subs may.

Youd need a REAL fast powder to burn a 100 grain charge in that short a barrel.

I would get some info from the sub companies and see what they recommend. Go with the fastest one.


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## rogerw

BBJ is right, but it also depends on what bullet you are going to use. All bullets begin moving long before the powder is burned and the heavier the bullet is, the longer it lingers giving the powder more time to burn.

A .50 patched round ball with 90gr 2F will have burned all the powder in about 30", although 95% is burned in 16" of barrel.

A .50 Maxiball with 90gr2F will have burned all the powder in about 22" of barrel and 95% in 11" of barrel.

Here is a calculated (not measured) graph of the interior ballistics of the Maxiball. To get the muzzle velocity scaled onto the rightside scale i had to divide by 40, so 35x40=1400fps and 30x40=1200fps, etc.










you can see how the pressure drops off quickly as the bullet moves up the barrel due to expansion of the hot gasses of combustion.

IMHO, the main thing about the shorter barrel is that you will get something like 100fps less MV, and that means about 15% less muzzle energy. With a patched roundball the percent losses are greater than with a heavy conical.

However, I generally prefer a 32" to 36" barrel not only for more complete combustion and higher MV, but for sighting radius on iron sights. I don't find it inconvenient for walking around as far as length goes.

YHS,
rogerw

I edited the chart to fix the left-scale label, and now this time to say that if you use a conical weighing less than the 370gr Maxi, you will get a result somewhere inbetween the 178grain PRB and the Maxi, of course.


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## Powerfisher

On my way to the range today to try out the BH209 sub. Do some research on it. It may be your ticket. I use a 28" w/1-28 twist, peep, and have no problem shouldering my rifle.


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## bluesman

I had another question. I know barrel length is proportional to caliber for round balls so what length barrel would use up all the powder in a hunting rifle of .54 caliber? I am pretty sure that the 42" barrels used on longrifles are not really needed, just overkill.


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## barebackjack

bluesman said:


> I had another question. I know barrel length is proportional to caliber for round balls so what length barrel would use up all the powder in a hunting rifle of .54 caliber? I am pretty sure that the 42" barrels used on longrifles are not really needed, just overkill.


Wrong.

Slow twists are the name of the game when it comes to stabilizing (I use the term loosely) roundballs.

I "roundball twist" in .54 caliber lingers around 1:60 or slower! So, the longer barrel helps to stabilize the round projectile by simply offering more distance for the rifling to impart its stabilizing spin to the projectile.

Also, longer barrels allow you to build more velocity by allowing you to use a larger charge (par for caliber of course-a long .50 cal barrel will allow you to fully use a larger charge than a shorter .50 cal barrel), and burn more of that charge in the barrel before the projectile leaves the muzzle. (If your burning the powder after the ball leaves the barrel, its all for nothing).

The evolution of the rifle went from the germanic hunting rifles, with their large caliber, short barrels. The Americans took the rifle, put a long, small caliber barrel on it. Part in due to the large expense related with powder/lead in colonial America (small caliber meant less lead per shot, and the longer barrel allowed smaller charges to be used while maintaining the same velocity that was seen in short barreled, large calibered rifles using far more powder).

And 42" is nothing. Ive got one with a 44" and another at 46"!!!

Not to mention, the long barreled flintlocks are a DREAM to shoot! They balance MUCH better than any modern "off the shelf" rifle. They seem to almost "float" on target.


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