Filler Question.

[Treebone]

Conventional wisdom suggests that we should use a filler in our muzzle loading revolver loads for two reasons.

1. To eliminate an air gap in the chamber which might result in an inconsistent burn rate.

2. To place the projectile closer to the breech thus allowing it to engage the rifling without a jump if it were to be seated deeper within the chamber.

My question takes us back to the time before the breech loading handgun ban in 1995 when smokeless powder was the most common propellant. Back then, the standard .38 Special revolver target load was around 2.8 grains of Bullseye behind a 148 grain Wadcutter lead bullet. The tiny amount of powder would have left a huge air gap in the .38 Special cartridge case and the Wadcutter bullet itself would have been completely seated within the case resulting in quite a big jump before the bullet entered the rifling. So, why is the use of a filler considered essential when using black powder loads, but doesn't seem to be necessary when using smokeless powder ?

Regards
Brian

Brian, no matter where you position your bullet in the chamber it still has to jump the gap between the cylinder and the forcing cone on the start of the breech of the barrel, loading it as close to the chamber mouth as you can wont make any difference to loading it half way down.

TB.

[tacfoley]

All the manufacturers of BP arms, and ALL the loading books, and everybody I've ever spoken to about the subject over the last fifty something years say exactly the same thing, as, indeed, all the demonstrators on YouTube, and everybody I've had contact with on muzzleloadingforum.com, many of whom are professional builders of muzzle loading firearms, often costing into five figures.

When loading ANY BP arm, even using substitutes, you leave an airgap at your own risk, IOW, DON'T DO IT. Short-loading any BP arm is fraught with danger, and that ball or bullet MUST be firmly seated on the charge.

You can argue and ask what if until the cows come home, but if you wish to carry out your own experiments into what happens if you don't, you are on your own. The list of bulged and/or burst barrels and missing body parts stretches from here to there and back again.

I've no more to add to that.

[Solvo]

You cannot really compare BP & substitutes to smokeless powder.
The firearms designed to use smokeless are far far stronger than any of the BR firearms on the market. Smokeless burns differently with a lower initial spike but a more prolonged pressure build up resulting in a higher overall chamber pressure.

You only need to look on YouTube and you'll find plenty of examples of people in the US showing what happens when you load a BP firearm with smokeless. It's mortally dangerous.
https://www.youtube.com/watch?v=Q_XNWeMqCT0

By the sound of the earlier replies the only people not using a filler ram the ball all the way onto the power anyway, regardless of the charge size.

And I'm with Tac 100%, Never ever load with an air gap for BP. I dont know how the physics of substitutes like Pyrodex & 777 work, but BP deflagrates (burns bloody fast) at a constant rate with oxygen present.
The air trapped in-between the grains is sufficient for the powder burn to build pressure to propel the projectile - However, if given more air the initial burn will last longer, this is where the term pressure spike comes from. BP builds more pressure than smokeless initially, but due to lack of air the pressure is only for a brief instant then the burn slows. The danger with the air gap is it provides enough air for the initial pressure spike to significantly increase to the point the firearm fails.

Edit - Good article here on longer air gaps cause by short loading the projectile for those who shoot long arms.
http://www.brimstonepistoleros.com/articles/squib.html

[enfield2band]

You cannot really compare BP & substitutes to smokeless powder.
The firearms designed to use smokeless are far far stronger than any of the BR firearms on the market. Smokeless burns differently with a lower initial spike but a more prolonged pressure build up resulting in a higher overall chamber pressure.

You only need to look on YouTube and you'll find plenty of examples of people in the US showing what happens when you load a BP firearm with smokeless. It's mortally dangerous.
https://www.youtube.com/watch?v=Q_XNWeMqCT0

By the sound of the earlier replies the only people not using a filler ram the ball all the way onto the power anyway, regardless of the charge size.

And I'm with Tac 100%, Never ever load with an air gap for BP. I dont know how the physics of substitutes like Pyrodex & 777 work, but BP deflagrates (burns bloody fast) at a constant rate with oxygen present.
The air trapped in-between the grains is sufficient for the powder burn to build pressure to propel the projectile - However, if given more air the initial burn will last longer, this is where the term pressure spike comes from. BP builds more pressure than smokeless initially, but due to lack of air the pressure is only for a brief instant then the burn slows. The danger with the air gap is it provides enough air for the initial pressure spike to significantly increase to the point the firearm fails.

Edit - Good article here on longer air gaps cause by short loading the projectile for those who shoot long arms.
http://www.brimstonepistoleros.com/articles/squib.html

Its the saltpetre (Potassium Nitrate) that provides the oxygen for blackpowder to burn.
Blackpowder is an explosive. It detonates and will do this outside a gun chamber.
If there is an air gap the powder gases start to expand. If they hit a solid such as a ball the pressure peaks at that point which causes the gun to burst. Without an air gap there is a progressive expansion of the gases that push the projectile out.

The peak pressure hitting a solid or obstruction also happens with smokeless. Several years ago there was what was termed a "Rash of Pimples" appearing on shotgun barrels.
It was eventually discovered that clay shooters who used the first barrel and did not fire the second barrel for a while was causing the crimp to weaken, due to the recoil, and allow the odd pellet to drop into the bore.
When they did fire the second barrel the charge hitting the loose pellet in the barrel caused the pressure to peak momentarily at that point and cause a tiny pellet sized bulge on the bottom of the barrel.
A larger obstruction would cause the pressure to peak higher and bulge or burst the barrel.

[Turnup]

Its the saltpetre (Potassium Nitrate) that provides the oxygen for blackpowder to burn.
Blackpowder is an explosive. It detonates and will do this outside a gun chamber.
If there is an air gap the powder gases start to expand. If they hit a solid such as a ball the pressure peaks at that point which causes the gun to burst. Without an air gap there is a progressive expansion of the gases that push the projectile out.

The peak pressure hitting a solid or obstruction also happens with smokeless. Several years ago there was what was termed a "Rash of Pimples" appearing on shotgun barrels.
It was eventually discovered that clay shooters who used the first barrel and did not fire the second barrel for a while was causing the crimp to weaken, due to the recoil, and allow the odd pellet to drop into the bore.
When they did fire the second barrel the charge hitting the loose pellet in the barrel caused the pressure to peak momentarily at that point and cause a tiny pellet sized bulge on the bottom of the barrel.
A larger obstruction would cause the pressure to peak higher and bulge or burst the barrel.

Agree with this mostly. Air in a BP load plays no part in the chemical reaction - BP has all the oxygen it needs already chemically bound in the Potassium Nitrate (which is released when heated and there is exactly enough oxygen to combine with the Carbon and Sulphur completely). The presence of an air gap changes the propagation of the deflagration reaction within the powder in unpredictable ways because the BP grains are not initially constrained to remain in one place. Sometimes you get away with it (I have fired a BP revolver where I had omitted the filler so the BP was loose - competition event and had no time to sort it - no harm done this time) and sometimes you don't. It does seem to be more of an issue with pistols than revolvers but this is not science.

Disagree on BP detonation. Detonation is defined as a deflagration (burning) reaction which proceeds through the deflagrating material supersonically. There is no known way to detonate smokeless. There is some suspicion that it is just about possible to detonate BP, but if it occurs at all it requires extreme conditions of a kind not encountered in firearms and even then the result is deflagration which is only marginally supersonic. Note that here I an referring to the speed of propagation of the reaction in relation to the speed of sound in the medium (in this case BP), and this is neither related to the speed of sound in air or the speed of the resulting projectile or combustion gasses.

BP requires some form of containment to produce a bang when ignited - free burning rate is not fast enough to go bang. A large amount of BP in a loose pile can self confine but it takes about a pound of the stuff to produce a bang rather than a "wuff". Small confinement (such as loose in an open ended cylinder) can produce a bang with much less material.

For these reasons BP is classed as a low explosive.

High explosives detonate well supersonically and produce characteristic shattering in metals rather than bending/stretching/tearing such as caused simply by overpressure.

It is my experience that:

a) reduced loads in revolvers can increase accuracy = this is analogous to the holy grail sweet spot Mv sought by many target shooters (air, rifle, and pistol/revolver).

b) seating the ball close to the chamber mouth is most likely to give the best results.

c) I do believe that there is also a sweet spot (or possible more than one) when seating the ball below the chamber mouth, at least in my ROA, but with no filler there are two variables (adjusting a BP only load varies seating depth and the resulting Mv) so it is difficult to experiment with any good control

[Abasmajor]

Agree with this mostly. Air in a BP load plays no part in the chemical reaction - BP has all the oxygen it needs already chemically bound in the Potassium Nitrate (which is released when heated and there is exactly enough oxygen to combine with the Carbon and Sulphur completely). The presence of an air gap changes the propagation of the deflagration reaction within the powder in unpredictable ways because the BP grains are not initially constrained to remain in one place. Sometimes you get away with it (I have fired a BP revolver where I had omitted the filler so the BP was loose - competition event and had no time to sort it - no harm done this time) and sometimes you don't. It does seem to be more of an issue with pistols than revolvers but this is not science.

Disagree on BP detonation. Detonation is defined as a deflagration (burning) reaction which proceeds through the deflagrating material supersonically. There is no known way to detonate smokeless. There is some suspicion that it is just about possible to detonate BP, but if it occurs at all it requires extreme conditions of a kind not encountered in firearms and even then the result is deflagration which is only marginally supersonic. Note that here I an referring to the speed of propagation of the reaction in relation to the speed of sound in the medium (in this case BP), and this is neither related to the speed of sound in air or the speed of the resulting projectile or combustion gasses.

BP requires some form of containment to produce a bang when ignited - free burning rate is not fast enough to go bang. A large amount of BP in a loose pile can self confine but it takes about a pound of the stuff to produce a bang rather than a "wuff". Small confinement (such as loose in an open ended cylinder) can produce a bang with much less material.

For these reasons BP is classed as a low explosive.

High explosives detonate well supersonically and produce characteristic shattering in metals rather than bending/stretching/tearing such as caused simply by overpressure.

It is my experience that:

a) reduced loads in revolvers can increase accuracy = this is analogous to the holy grail sweet spot Mv sought by many target shooters (air, rifle, and pistol/revolver).

b) seating the ball close to the chamber mouth is most likely to give the best results.

c) I do believe that there is also a sweet spot (or possible more than one) when seating the ball below the chamber mouth, at least in my ROA, but with no filler there are two variables (adjusting a BP only load varies seating depth and the resulting Mv) so it is difficult to experiment with any good control

Hello,

Thanks for the comprehensive explanations from both yourself and others who have kindly contributed to this thread and helped me gain a better understanding of the reasons for using filler in BP revolver loads.

I'm still not convinced about the necessity of seating the ball close to the chamber mouth though because as stated in the original post, the recommended precision target load for nitro revolvers before the 1995 breech loading pistol ban used a 148 grn Wadcutter bullet necessarily seated a long way from entry to the breech necessitating quite a big jump before engaging the barrel rifling.

Brian

[loiner1965]

i dont reload bp this way but a few lads i know from another forum do..
basically they load martini henrys with 85gns of bp with no filler other than the grease cookies and cards in the neck.
they say mr greener and others said leaving up to 20% air space in a cartridge was acceptable with no issues.
these are not my words but others

[Turnup]

Hello,

Thanks for the comprehensive explanations from both yourself and others who have kindly contributed to this thread and helped me gain a better understanding of the reasons for using filler in BP revolver loads.

I'm still not convinced about the necessity of seating the ball close to the chamber mouth though because as stated in the original post, the recommended precision target load for nitro revolvers before the 1995 breech loading pistol ban used a 148 grn Wadcutter bullet necessarily seated a long way from entry to the breech necessitating quite a big jump before engaging the barrel rifling.

Brian

Er....when downloading a pistol cartridge such as .38 spl or .357 magnum, the much reduced nitro charge (IIRC 2.7 grains of Bullseye was a popular load) leaves a very large airspace in the cartridge. The bullet is seated to exactly the same place with a reduced charge as with a full load, thus keeping the COL within spec and thus placing the bullet at exactly the same distance from the chamber mouth. Seating a .38 spl to zero airspace with 2.7 grains of Bullseye (even if it were possible, could not be done any seating dies I have seen) would leave the bullet wholly inside the case, and nothing to crimp on.

[enfield2band]

Agree with this mostly. Air in a BP load plays no part in the chemical reaction - BP has all the oxygen it needs already chemically bound in the Potassium Nitrate (which is released when heated and there is exactly enough oxygen to combine with the Carbon and Sulphur completely). The presence of an air gap changes the propagation of the deflagration reaction within the powder in unpredictable ways because the BP grains are not initially constrained to remain in one place. Sometimes you get away with it (I have fired a BP revolver where I had omitted the filler so the BP was loose - competition event and had no time to sort it - no harm done this time) and sometimes you don't. It does seem to be more of an issue with pistols than revolvers but this is not science.

Disagree on BP detonation. Detonation is defined as a deflagration (burning) reaction which proceeds through the deflagrating material supersonically. There is no known way to detonate smokeless. There is some suspicion that it is just about possible to detonate BP, but if it occurs at all it requires extreme conditions of a kind not encountered in firearms and even then the result is deflagration which is only marginally supersonic. Note that here I an referring to the speed of propagation of the reaction in relation to the speed of sound in the medium (in this case BP), and this is neither related to the speed of sound in air or the speed of the resulting projectile or combustion gasses.

BP requires some form of containment to produce a bang when ignited - free burning rate is not fast enough to go bang. A large amount of BP in a loose pile can self confine but it takes about a pound of the stuff to produce a bang rather than a "wuff". Small confinement (such as loose in an open ended cylinder) can produce a bang with much less material.

For these reasons BP is classed as a low explosive.

High explosives detonate well supersonically and produce characteristic shattering in metals rather than bending/stretching/tearing such as caused simply by overpressure.

It is my experience that:

a) reduced loads in revolvers can increase accuracy = this is analogous to the holy grail sweet spot Mv sought by many target shooters (air, rifle, and pistol/revolver).

b) seating the ball close to the chamber mouth is most likely to give the best results.

c) I do believe that there is also a sweet spot (or possible more than one) when seating the ball below the chamber mouth, at least in my ROA, but with no filler there are two variables (adjusting a BP only load varies seating depth and the resulting Mv) so it is difficult to experiment with any good control

I don't disagree with what you are saying. I think we are looking at this differently.

I have read somewhere that the detonation velocity of blackpowder is about 950fps. Thus explosives are,as far as I am aware, determined by their detonation velocity. SEMTEX has a detontaion velocity of 5 mile per second, which is why I used the term detonation. Blackpowder changes from a solid to a gas when ignited even when unconfined. As you know smokeless does not, it burns very rapidly.

[Turnup]

I don't disagree with what you are saying. I think we are looking at this differently.

I have read somewhere that the detonation velocity of blackpowder is about 950fps. Thus explosives are,as far as I am aware, determined by their detonation velocity. SEMTEX has a detontaion velocity of 5 mile per second, which is why I used the term detonation. Blackpowder changes from a solid to a gas when ignited even when unconfined. As you know smokeless does not, it burns very rapidly.

The deflagration velocity of BP is about what you have stated. This is subsonic even in air and far less than the speed of sound in solids - while it is believed possible to detonate BP it is extremely difficult to do so and certainly not in the conditions encountered in a firearm. Even initiation of BP using a detonating booster (i.e one which produces a supersonic shockwave) is unlikely to detonate the BP itself and attempts to do so have been inconclusive. BP DOES NOT HAVE A RECOGNISED DETONATION VELOCITY (for that matter neither does smokeless).

Smokeless also changes from a solid into gasses when ignited, even unconfined. What did you think it does? Smokeless at or about atmospheric pressures burns (deflagrates) quite slowly, whereas BP burns much faster at atmospheric pressures, but the burn rate increases much more slowly as pressure increases (in fact practically linearly) whereas the deflagration rate for smokeless increases exponentially with increasing pressure.