Why use filler?
A question that frequently comes up for debate is the use of filler in black powder firearms, particularly revolvers.
So first of all, what is "filler"? Filler is some kind of inert substance that is put on top of the powder charge, but under the projectile. Some common fillers are cream of wheat or cornmeal.
Many people say, "Why would you want to use a filler? Period black powder firearms did not use a filler!"
And that is true. But we have to remember a couple of things about Civil War-era black powder military firearms.
First and foremost, they were looking for knock-down power. So generally they wanted the biggest bang that the firearm could tolerate so as to deliver the most energy on target and get the most range out of the projectile. This is how they arrived at their "service charges".
The other thing to remember is that some period firearms, especially revolvers, had very different rifling than modern reproductions do. Most modern reproduction black powder revolvers have had their twist rates optimized for round ball. But many period black powder revolvers had gain-twist rifling, or rifling otherwise optimized for conical ball bullets. So loads that worked optimally in an original revolver may not work in a reproduction.
Shooting For Accuracy
The first thing to note is you will almost certainly not achieve maximum precision (the tightest possible group) with the full military service charge. This is generally true for all military black powder arms, but especially true for revolvers. You will probably find, for example, that most .44 revolvers, like the Colt 1860 or the Remington New Model Army (1858) develop best accuracy around 18-20 grains of 3F powder. Their service charges were typically 30 grains or so. The Walker reproductions generally develop best accuracy around 45 grains of 3F powder, and its service charge was 60 grains or so.
When you seat a bullet in a black powder revolver, you should seat it until it bottoms out against the charge. You should not leave an air gap between the powder and the ball. You will find this admonition in the owner's manual of most reproductions. The reason is for safety - an air gap might cause the bullet to act like a bore obstruction and possibly damage the cylinder during firing. Another reason is it keeps the powder backed firmly at the rear of the cylinder where it is most likely to be set off by the percussion cap flash.
If you are shooting a reduced charge for accuracy, this means that you will end up seating your bullet quite deeply in the chamber. What this means is that when you fire the chamber, the bullet will have worked up quite a bit of velocity before striking and engaging the rifling. This can make it strip on the rifling rather than take up the rifling and spin the bullet.
With modern cartridge firearms, many competition shooters will adjust the COAL - cartridge overall length - so that the ogive of the bullet is just touching the rifling when the cartridge is chambered. This is done so that the bullet will immediately engage the rifling as soon as it starts to move.
Additionally, some revolvers do not have chambers that are completely cylindrical. Some of them are slightly conical and get smaller in diameter the deeper into the chamber you go. This is especially true if your cylinder has reamed chambers where perhaps only the first third or so of the chamber has been reamed. In this case, as you drive the bullet deeper into the chamber, the smaller diameter chamber walls will swage the bullet down correspondingly smaller also. This can harm accuracy if you end up with a bullet smaller in diameter than is optimal for your bore size.
So, ideally, in our revolvers we want our bullets seated flush with the cylinder face. But with a reduced charge, we would have an air gap if we do that. Hence the need for a filler.
To use a filler, you simply pour your powder into the chamber, and then pour a measured amount of filler on top of the powder, and then you seat your ball. With the correct amount of powder and filler, the ball will bottom out and compress the charge and filler and end up with the nose of the bullet flush with the cylinder face. It is important that you are no more than flush because if the nose of the bullet stands proud it will hit the barrel as the cylinder rotates and lock up the cylinder.
How much powder / filler to use?
The only way to determine the right load for your firearm is to do a load workup.
What this entails is trying different amounts of powder until you find the amount, with the appropriate amount of filler to keep the ball flush with the cylinder face, that gives you the tightest group possible.
For a .44 caliber revolver (except the Walker), you might start with 14 grains of 3F and work your way up to 30 grains in 2-grain increments. For the Walker you might start with 35 grains and work up to 55.
And of course feel free to experiment without filler, while seating the ball firmly on the powder. You might find that you get best accuracy without it. I have not ever found that to be the case, but you never know until you try!
So first of all, what is "filler"? Filler is some kind of inert substance that is put on top of the powder charge, but under the projectile. Some common fillers are cream of wheat or cornmeal.
Many people say, "Why would you want to use a filler? Period black powder firearms did not use a filler!"
And that is true. But we have to remember a couple of things about Civil War-era black powder military firearms.
First and foremost, they were looking for knock-down power. So generally they wanted the biggest bang that the firearm could tolerate so as to deliver the most energy on target and get the most range out of the projectile. This is how they arrived at their "service charges".
The other thing to remember is that some period firearms, especially revolvers, had very different rifling than modern reproductions do. Most modern reproduction black powder revolvers have had their twist rates optimized for round ball. But many period black powder revolvers had gain-twist rifling, or rifling otherwise optimized for conical ball bullets. So loads that worked optimally in an original revolver may not work in a reproduction.
Shooting For Accuracy
The first thing to note is you will almost certainly not achieve maximum precision (the tightest possible group) with the full military service charge. This is generally true for all military black powder arms, but especially true for revolvers. You will probably find, for example, that most .44 revolvers, like the Colt 1860 or the Remington New Model Army (1858) develop best accuracy around 18-20 grains of 3F powder. Their service charges were typically 30 grains or so. The Walker reproductions generally develop best accuracy around 45 grains of 3F powder, and its service charge was 60 grains or so.
When you seat a bullet in a black powder revolver, you should seat it until it bottoms out against the charge. You should not leave an air gap between the powder and the ball. You will find this admonition in the owner's manual of most reproductions. The reason is for safety - an air gap might cause the bullet to act like a bore obstruction and possibly damage the cylinder during firing. Another reason is it keeps the powder backed firmly at the rear of the cylinder where it is most likely to be set off by the percussion cap flash.
If you are shooting a reduced charge for accuracy, this means that you will end up seating your bullet quite deeply in the chamber. What this means is that when you fire the chamber, the bullet will have worked up quite a bit of velocity before striking and engaging the rifling. This can make it strip on the rifling rather than take up the rifling and spin the bullet.
With modern cartridge firearms, many competition shooters will adjust the COAL - cartridge overall length - so that the ogive of the bullet is just touching the rifling when the cartridge is chambered. This is done so that the bullet will immediately engage the rifling as soon as it starts to move.
Additionally, some revolvers do not have chambers that are completely cylindrical. Some of them are slightly conical and get smaller in diameter the deeper into the chamber you go. This is especially true if your cylinder has reamed chambers where perhaps only the first third or so of the chamber has been reamed. In this case, as you drive the bullet deeper into the chamber, the smaller diameter chamber walls will swage the bullet down correspondingly smaller also. This can harm accuracy if you end up with a bullet smaller in diameter than is optimal for your bore size.
So, ideally, in our revolvers we want our bullets seated flush with the cylinder face. But with a reduced charge, we would have an air gap if we do that. Hence the need for a filler.
To use a filler, you simply pour your powder into the chamber, and then pour a measured amount of filler on top of the powder, and then you seat your ball. With the correct amount of powder and filler, the ball will bottom out and compress the charge and filler and end up with the nose of the bullet flush with the cylinder face. It is important that you are no more than flush because if the nose of the bullet stands proud it will hit the barrel as the cylinder rotates and lock up the cylinder.
How much powder / filler to use?
The only way to determine the right load for your firearm is to do a load workup.
What this entails is trying different amounts of powder until you find the amount, with the appropriate amount of filler to keep the ball flush with the cylinder face, that gives you the tightest group possible.
For a .44 caliber revolver (except the Walker), you might start with 14 grains of 3F and work your way up to 30 grains in 2-grain increments. For the Walker you might start with 35 grains and work up to 55.
And of course feel free to experiment without filler, while seating the ball firmly on the powder. You might find that you get best accuracy without it. I have not ever found that to be the case, but you never know until you try!