Article #10: Buffers, Fillers, and other "taboo" subjects

Ian

Well-Known 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.
 
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Ian

Well-Known Member
(Continued).....

Principally, I only use one thing for buffer as a matter of safety: BPI Original granular shotshell buffer used in ball, slug, and buckshot loads to help support the soft lead projectiles under acceleration and keep them from deforming. There are other things to use, but I won't go into them here except Cream O' Wheat, and only to add another disclaimer. COW is hygroscopic absorbs atmospheric or other moisture), and tends to form a starchy, solid mass when allowed to sit in a loaded cartridge case for any length of time, and this can cause a serious obstruction when fired since it won't compress and squeeze through a bottlenecked rifle case as easily as it does when it's dry, flexible, and fluffy. It typically absorbs moisture from the smokeless powder (or even gunpowder) itself when put in a cartridge case, and that increases the effective burn rate of the powder drastically, so it's a sort of "one, two punch" on raising the hell out of pressure in a stored load that's otherwise perfectly safe when fired the same day it's put together. Back to the BPI Original (not to be confused with the spherical version that is a true filler as I described earlier). In some instances, particularly high-powered rifles in which I'm attempting to achieve very high velocity and maintain accuracy, I use this PSB (polyethylene shotshell buffer) to fill the space between the powder and bullet base, with slight compression....


...What happens then is the buffer works against the restriction formed by the shoulder of the case to add more resistance to the powder pressure. More resistance=higher temperatures which=higher efficiency which=more consistent shot-to-shot burn which=smaller groups. This is a trick to get slow powders that we like for gentle launches of our delicate bullets to burn well, yet still not build too much pressure too soon. There is a delicate balance here since too much of a good thing raises pressure too much before the bullet moves and defeats the purpose of using slow, hard to light powder. The buffer extrudes into the neck and pushes the bullet into the throat without it being touched by the gas, so the neck expands behind the bullet as it moves forward rather than blowing past the base of the bullet and expanding the neck before the bullet moves as often happens with a high pressure load without buffer but with a well-fitting nose that obturates the throat. All that adds to accuracy. Oh, and the buffer plug follows the bullet all the way out the muzzle, shielding the bullet base from the yawing effects of muzzle blast at crown exit.


How much powder, what kind of powder, which cases to use it in, how much buffer, and particularly how much static compression to use is a little bit beyond what I'm trying to cover here in this post, and gets into the Twilight Zone of Ph, D. handloading, so I'd rather address it on a very specific and individual basis rather than attempt to establish general guidelines for its use. Sorry for the letdown, but feel free to ask specific questions if you're serious about applying buffer to a load and I'll share what I know.
 
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Ian

Well-Known Member
(Continued)....

Now don't go to sleep, because THIS IS IMPORTANT!: Fiber fillers and wads must be used correctly or at the least you can "ring" your chambers. You've probably heard the term "chamber ringing" associated with the use of "fillers", along with the palpably nervous hush and furtive glances among those that consider putting anything inside a case other than powder and air is foolish and will always ruin your gun. While I certainly respect those who never step outside of well-established, published loading practices, there are some of us who, like Doral, "Imagine getting more" from our cast bullet loads and have learned how to safely and properly use fillers and wads to help us out occasionally. Chambers are ringed by one thing, and that's the IMPROPER use of fillers and wads. The sudden, high pressure, radial pressure wave deflected off of the bullet's base because the reloader didn't follow directions and tamped the filler/wad down on top of the powder and left an air gap between it and the bullet base is what caused the problem, not any mystical, inherent danger of a few tufts of fibers or a little disc of cardstock. When you compress the powder into a column and leave a big gap in between it and the bullet, the bullet becomes a bore obstruction. The powder lights and burns ferociously because it's crammed against the primer, then it pushes the wad forward (be it card, fiber, or a tamped tuft of Dacron or similar) like a piston that slams suddenly into the boolit base with tremendous force like a freight train hitting a concrete wall. Usually it doesn't blow the chamber before the bullet moves, but that force is directed outward as it concentrates behind the mass of the bullet, often stressing the chamber steel enough to form a permanent ring right behind where the bullet base is parked.


The proper way to use a fiber filler is to fluff, or "loft" it up when installing it in the case such that it occupies all of the space between bullet and powder. I don't mean pack it in there tightly, but let it have a little compression beyond what the fibers naturally have if you wad them in your hand and allow them to relax to their natural volume. I like Dacron for some loads because it has a very consistent, robust, natural springy loft to it and I can poke a tuft of it down into a bottlenecked case with a pocket screwdriver or blunted nail, leave a little bit up in the neck, seat a bullet, and know it's properly compressed and not going to ring my chamber. Lint, cotton, and wool don't have as much spring, tend to start wildfires, and can get sort of packed down like an old pillow through handling or recoil in a magazine, thus potentially becoming a wad against the powder and leaving the air gap we want to avoid.


The proper way to use a fiber or card wad, (true WADS in my mind at least, and notwithstanding the muzzle-loading, gunpowder guys) is right under the bullet, or in shotgun shells. Notice how shotgun shells are ALWAYS supposed to be loaded to 100% density? Heavy payloads, fast powders, and thin chambers are a recipe for rings if ever there was one, but how many have ever seen a ringed shotgun chamber from a properly assembled shotshell? Some of them are using a half-inch of wadding or more, but it's done so the powder column can't get a head start before it slams into the payload. Engineered crush zones have largely replaced separate overpowder wads in commercial offerings, but again, they cushion and build gradual resistance until the payload moves. I only use card wads in one instance, and that's in a high-pressure, paper-patched load involving a cartridge case that simply runs out of room for any other kind of buffer, but needs one to help protect the bullet base. I get a significant reduction in group size with my .45 Colt carbine launching a 340-grain, soft lead paper-patched slug out of an 18" barrel at over 1300 fps when adding a hard wad cut from soda can 12-pack cartons. The load is compressed already, nothing but as much Reloader 7 as I can pack in there.


Ok, in review, I only recommend Dacron fiberfill for powder location beween boolit and powder column and only in slight compression; I only use granular, PSB as a compacting buffer, and only then in specialized, high velocity applications; don't leave air gaps between your wads and the boolit base, and thanks for reading this!


Ian
 

KHornet

Well-Known Member
Most excellent thread Ian! Agree with you! Over more years than I care to think about, I have used fillers in various forms from toilet paper and kapok from an old life saving vest, and a few others in between until the advent of Dacron. The only fillers such as COW that I have ever used successfully have been with straight walled cases (444/45-70), and they did leave the bores very shiny. However got no better accuracy than with Dacron so that test stopped there. Have heard of COW fillers used in bottle neck cases forming a plug over time, raising pressure, and I believe I recall one blown rifle as a result years back. It has long been my practice (probably over 30 years to use Dacron fill in rifles with cast bullets over any charge of less than half a case full( and by half case I mean half of the amount to the mouth of the case. I use small amounts of pulled Dacron fiber, rather than the little cut squares of the sheet type Dacron, as I find it to be more consistent in weight by eyeballing the quantity. Very, very slight compression as you suggest between powder and bullet base is all that is needed. When I first started using Dacron, I was obviously using to much as I had some fibers floating out in front of the bbl after the shots, and am sure that increased pressure. By reducing the amount of Dacron to a minimum between powder and bullet base, I have not seen any fiber in the air in many years as it is consumed. Again, excellent thread! Thanks.
 

JWFilips

Well-Known Member
Dacron here with slower powders : but I don't see the need for it : The faster less position sensitive powders do better in all my rifle loads so far from .223 to .35 cal.
but again I never am lookiing at the 2000 + fps level so that may be the factor
 

Ian

Well-Known Member
"Nobade" from the CB forum, who is also a member here, has invented a really unique type of filler he calls "reactive filler". I'll let him explain it, but essentially he's using an extremely slow-burning powder to top off a slightly reduced charge of medium-ish powder. This works like buffer and progressive powder at the same time, pretty cool stuff.
 

Brad

Administrator
Staff member
The reactive filler idea is pretty interesting. Using a very slow powder as a buffer that also gives abot of extra boost is certainly innovative.
 

45 2.1

Active Member
^^^^^^^ Neither is new. Those concepts were used in the late 1800's with BP. If you go over to British Militaria, you would see the black powder loaders using that term "reactive filler" in another way also long before it was heard elsewhere.
 

Snakeoil

Member
Hi,
New guy here. Not new to Earth, but new to smokeless loads in straight-wall BP cases, specifically .45-70. The rifle is a Shiloh Sharps that has been with me for many years and never seen anything other than BP. But I'm getting tired of the stench, filth and PITA piece of shooting BPCR matches, and our local club has relaxed the rules to allow smokeless loads with lead bullets.

I've been doing a lot of reading on the topic. Back when I first got the rifle, about 15 years ago, other shooters were talking about reduced loads using Unique. But they came with the old "detonation" legend/risk and although I tried them when I was breaking the barrel in (guess she has seen smokeless in the past) I never loaded or shot more than 100 rounds with Unique. I don't remember the load I used. But for sure, never used any type of wadding.

Looking at the Lyman manual, they show a number of smokeless loads for the cartridge with pressures geared towards Trapdoors, Lever Guns and modern, high strength actions. Every one of them includes what Lyman calls a Dacron Wad, 5/8" square by 1/4" thick.

My concern is ringing the chamber. This article (thanks for taking the time to post in such detail, Ian) explains a lot and I'm feeling much better about it than I did about a week ago. The shotshell analogy drove the point home because I have put tens of thousands of 12 ga rounds thru trap guns, all reloads with never a problem or concern. The obvious question is why would a .45 cal brass case with a 400 gr slug and a chamber wall like a naval gun not tolerate a cushioned wad when a shotshell in a plastic case pushing 500 gr of lead with a much thinner chamber be okay with it? Now I get it.

But, I have to ask, if I use a powder like 2400, which is supposedly not sensitive to position and hence with a low, to no risk of "detonation", is a fiber wadding like Dacron necessary?

Sorry, if I am bringing up the equivalent to an "oil thread" that is dreaded and hated in the car and motorcycle world, please forgive me. But I prefer to use the KISS principle whenever I can and not using a Dacron wadding would be in keeping with that. But if it is foolhardy, I'll gladly include the tweezering of Dacron wadding into each case.

Thanks,
Rob
 

popper

Well-Known Member
I use dacron over Unique in 30/30 but not when loading 2400. Primarily as a powder positioner. Why? I read the Federal article on primers. And understand the slow coated powders. Primers ignite the powder with hot metal slag, not hot gasses. I watched some brusience videos years ago and you can actually see the 'sparks' fly. Now with some powder laying in the bottom of the case, fast pistol stuff gets ignited from adjacent burn. Slower coated powders burn is erratic. Gases (and metal) from the powder move supersonically to fill the case - the high pressure adds energy to the 'burn' of the powder but the burn can be 'spotty'. Bunching the powder with filler reduces the 'spottyness' of the ignition. This sporadic burning creates several high pressure waves that collide and create extremely high pressure areas that can 'ring' a chamber. Why do I hold to this 'theory'? From extensive solid propellant rocket motor tests. Burn rate is controlled by surface area and cracks or distortions in the solid change the burn rate, create high pressure reflecting waves the rupture the casing.
 

Ian

Well-Known Member
It sounds to me that the KISS principle will lead to buying a can of IMR Trail Boss and following published data. Use a good, soft lube with that stuff.

There's a difference between using a filler as an optional powder location mechanism to promote consistent pressure curves from shot to shot and using a filler as an essential safety mechanism with heavily-deterred powders at less than optimum loading density. Unless you're going off the map into la-la-land with 20mm cannon powder, a duplexed kicker charge, and granular buffer to keep the column stacked properly, pretty much any published smokeless powder recipe will satisfy your needs without any fillers.
 

fiver

Well-Known Member
I wouldn't be too quick to believe 2400 isn't position sensitive either.
it got that reputation in handgun cases where the fill volume is high enough that up or down didn't matter.
 

Brad

Administrator
Staff member
2400 has given me strong indications of being position sensitive in 45-70. I still use it with no filler as the 2” or so of vertical at 100 just aren’t enough to justify the filler.
 

Ian

Well-Known Member
Yes, 2400 is position-sensitive in any cartridge where the loading density is less than about 90%. In many instances it can be pretty extreme.

The only powder I've found so far to be virtually immune to position-sensitivity is Titegroup.
 

25ring

New Member
It sounds to me that the KISS principle will lead to buying a can of IMR Trail Boss and following published data. Use a good, soft lube with that stuff.

There's a difference between using a filler as an optional powder location mechanism to promote consistent pressure curves from shot to shot and using a filler as an essential safety mechanism with heavily-deterred powders at less than optimum loading density. Unless you're going off the map into la-la-land with 20mm cannon powder, a duplexed kicker charge, and granular buffer to keep the column stacked properly, pretty much any published smokeless powder recipe will satisfy your needs without any fillers.
I've been running the 20mm powder plus kicker charge in my trapdoor for about 6yrs,it needs no fillers or buffers.It loads like BP, a case full with a .030 wad slightly compressed and a cast bullet of your choice. Loads without the kicker run around 1150-1200 fps,with a 4gr RL7 kicker 1300-1350. I've been able to get SD's in the single digits. Without a kicker charge you can't get enough powder in the case to get you in trouble,too much kicker all bets are off.FWIW
 
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Ian

Well-Known Member
In a 45/90 WCF I like about .3" of polyethylene buffer on top of the cannon powder to dumb the load down a little for less recoil. RX-7 and IMR 4198 both make excellent kickers. I didn't mean to imply that "la-la-land" is a bad place, you'd just better understand what the heck you're doing if you go there.
 

25ring

New Member
In a 45/90 WCF I like about .3" of polyethylene buffer on top of the cannon powder to dumb the load down a little for less recoil. RX-7 and IMR 4198 both make excellent kickers. I didn't mean to imply that "la-la-land" is a bad place, you'd just better understand what the heck you're doing if you go there.
That's for sure! In my 45-90 I settled on a 3 wad stack after trying floral foam and buffers,the chronograph numbers just seemed to be a little better for me. I'm using a paper patched bullet with very little in the case so maybe the wad stack gives me more consistant compression.
 

RicinYakima

High Steppes of Eastern Washington
All I can say is that I still have two CBA National Records with the Trapdoor 45/70 with the 24 grains of A2400 at 100 and 200 yards. No wads, positioner or anything else is used. HOWEVER I hold the rifle level, tap the rim on the action and gently lower the case and close the block. IMHO, A2400 is very lightly deterrent coated and has enough nitroglycerin in the formula to ignite easily with my WW LR standard / magnum primers. FWIW, Ric
 

Brad

Administrator
Staff member
What bullet weight Ric?
I love 24 gr of 2400 with a 420 gr plainbase. It is my go to load for my Marlin 45-70. Just shoots so good.
 

RicinYakima

High Steppes of Eastern Washington
My 100 yard record was with the Lee 405 HB, the only record every made with a Lee mould, from linotype. Know it is not suppose to work, but it does. . The 200 yard with a Hoch 475 grain RNFP, WW with 2% tin. The issue is always finding a mould that will cast .463", my chamber diameter. My Handi-Rifle used the Lyman 457193 for the Marlin lever gun, polished out to size. HTH, Ric