Filler Question.

[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

[tacfoley]

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

Please go right ahead and try it out for us.

We are eager to see your results.

BTW, loading 85gr AND grease cookies in a .577-450 doesn't actually leave ANY airspace, in my experience, at least. YMMD.

20% air gap? Might be OK. But basically the practice of leaving a LARGE airspace between a bullet/ball and load WILL result in damage to a BP firearm, ranging from mild ringing to catastrophic failure of the barrel at just about the point where your hand is holding it. Did you even look at the CVA YouTube movie?

[loiner1965]

tac...
i myself dont leave airspace in 577 / 450 rounds at all , weather i use betram / kynock or much larger capacity cbc cases which can swallow 120gns of bp.
i tend to use around 60gns of swiss and 3 gns of kapok.
another forum i frequent is the the british military forum where many experienced shooters shoot martinis with 85gns and air as the filler....
please check it out.....https://www.tapatalk.com/groups/...r+space#p18340

[tacfoley]

tac...
i myself dont leave airspace in 577 / 450 rounds at all , weather i use betram / kynock or much larger capacity cbc cases which can swallow 120gns of bp.
i tend to use around 60gns of swiss and 3 gns of kapok.
another forum i frequent is the the british military forum where many experienced shooters shoot martinis with 85gns and air as the filler....
please check it out.....https://www.tapatalk.com/groups/...r+space#p18340

I only load .45-70 Govt, and leave no air-space at all, by using a drop-tubed load that allows of around 1/8th inch compression when loading the usual 405gr bullet. By all means continue to do what you have always done - same goes for your acquaintances and their empty spaces.

I guess I've nothing more to add to this thread.

[loiner1965]

I only load .45-70 Govt, and leave no air-space at all, by using a drop-tubed load that allows of around 1/8th inch compression when loading the usual 405gr bullet. By all means continue to do what you have always done - same goes for your acquaintances and their empty spaces.

I guess I've nothing more to add to this thread.

those who leave air spaces in bp cartridges do not do it to be different or start a trend etc..
they have read articles and books by gun makers like mr greener and others.....so its not taken lightly.
one chap i know shoots competitions all over europe and fires 1000s of rounds without incident or chamber ringing of any sort.
myself i stick to using kapok as i only shoot bp occasionally.
remember many people still use cream of wheat in bottle neck cases and dont realise they can cause case / neck separations and have been shooting that way for years without incident......pays ya money and take ya chances

[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.