Ian
Notorious member
The Basement Articles #10: Buffers, fillers, and other taboo subjects
Three things we need to talk about here: FILLERS, BUFFERS, and WADS.
These all have their place when assembling cast bullet loads, although I generally try to avoid them for most work as all of them are more or less "bandages" for other problems. For some ends,though, the proper application of these things is a practical way to achieve them. I'll attempt to explain.
Fillers and buffers are two different things to me, although some use the term interchangeably. The reason I differentiate is that I frequently use buffers as a tool to achieve some particular, and potentially dangerous ends that many people don't fool with. The term "wad" is perpetually misused, oftentimes probably where "wadding" would have been more descriptive, but who knows.
Fillers are, to me, the fluffy ones like Dacron, Kapok, dryer lint, wool, cotton, Styrofoam packing peanuts, florist's foam, "fake" snow, cat hair, etc. Fillers don't raise pressure much, although they do promote efficient combustion by fooling the powder into thinking it is in a smaller cartridge case than it actually is during initial combustion, and also by locating the powder positively against the primer where it can get maximum exposure to the primer's heat. I like to call fillers "powder locators" because essentially that's what I use them for. The filler easily compresses forward as the primer blast goes off and early burn pressure begins, so the case volume is rapidly and gently expanded to "normal" and the powder continues to burn almost as if the filler weren't there.
Intermediate sorts of fillers are things like Puff-Lon (or however it's spelled), spherical HDPE pellets like some of the shotshell buffers, and other things that don't compress into a solid plug under pressure. These "flowing" fillers have more mass than the fibrous fillers, take up A LOT more volume under pressure, and loads must be reduced considerably when using them, but they don't tend to seal gas from the bullet base. Basically, they're true fillers because they effectively reduce case volume even at peak pressure.
Buffers are something I learned about from two guys on the Castboolits forum who rarely post anymore, so I'm preserving the technique, and my experiences of it's use here for posterity. I don't know if it was all their idea, but it certainly wasn't mine, although once the seed was planted I more or less learned how to use it on my own. Buffers are things that compact into a solid plug under pressure, increase loading density, tend to clump rather than flow, and can effectively relay the kinetic energy of the burning powder gas to the bullet without the gas actually touching it. They must fill the case and achieve slight compression to locate the powder, prevent mixing, and to work as a "buffer" between bullet and hot burning gas. This last is why we use the term "buffer" rather than filler, even though it serves the other purposes automatically.
My comments here on buffers and how I use them are made with the assumption that you realize that you can very easily kill or maim yourself or others using them if you don't know exactly what you're doing, so don't take this information lightly. Neither the site owners nor I will assume any responsibility whatsoever for anyone who chooses to use this information.
Three things we need to talk about here: FILLERS, BUFFERS, and WADS.
These all have their place when assembling cast bullet loads, although I generally try to avoid them for most work as all of them are more or less "bandages" for other problems. For some ends,though, the proper application of these things is a practical way to achieve them. I'll attempt to explain.
Fillers and buffers are two different things to me, although some use the term interchangeably. The reason I differentiate is that I frequently use buffers as a tool to achieve some particular, and potentially dangerous ends that many people don't fool with. The term "wad" is perpetually misused, oftentimes probably where "wadding" would have been more descriptive, but who knows.
Fillers are, to me, the fluffy ones like Dacron, Kapok, dryer lint, wool, cotton, Styrofoam packing peanuts, florist's foam, "fake" snow, cat hair, etc. Fillers don't raise pressure much, although they do promote efficient combustion by fooling the powder into thinking it is in a smaller cartridge case than it actually is during initial combustion, and also by locating the powder positively against the primer where it can get maximum exposure to the primer's heat. I like to call fillers "powder locators" because essentially that's what I use them for. The filler easily compresses forward as the primer blast goes off and early burn pressure begins, so the case volume is rapidly and gently expanded to "normal" and the powder continues to burn almost as if the filler weren't there.
Intermediate sorts of fillers are things like Puff-Lon (or however it's spelled), spherical HDPE pellets like some of the shotshell buffers, and other things that don't compress into a solid plug under pressure. These "flowing" fillers have more mass than the fibrous fillers, take up A LOT more volume under pressure, and loads must be reduced considerably when using them, but they don't tend to seal gas from the bullet base. Basically, they're true fillers because they effectively reduce case volume even at peak pressure.
Buffers are something I learned about from two guys on the Castboolits forum who rarely post anymore, so I'm preserving the technique, and my experiences of it's use here for posterity. I don't know if it was all their idea, but it certainly wasn't mine, although once the seed was planted I more or less learned how to use it on my own. Buffers are things that compact into a solid plug under pressure, increase loading density, tend to clump rather than flow, and can effectively relay the kinetic energy of the burning powder gas to the bullet without the gas actually touching it. They must fill the case and achieve slight compression to locate the powder, prevent mixing, and to work as a "buffer" between bullet and hot burning gas. This last is why we use the term "buffer" rather than filler, even though it serves the other purposes automatically.
My comments here on buffers and how I use them are made with the assumption that you realize that you can very easily kill or maim yourself or others using them if you don't know exactly what you're doing, so don't take this information lightly. Neither the site owners nor I will assume any responsibility whatsoever for anyone who chooses to use this information.
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