Dacron fiber fillers?????

[jh45gun]

I want to load some cast loads using Unique powder and cast bullets for the following cartridges. 45/70, 30/30, 308, 8mm, and 762x54. I have read in the past good and bad of using fiber fillers??? I know the lyman book used to recomend them and I tried to call them but they were closed. I called Alliant powder and they said they never tested fillers and to contact Lyman. What is every ones take here on the subject. I would like to load loads to get my cast bullets in the 1600 fps area plus or minus depending on the cartridge. I have heard that fiber fillers cause too much pressure and then I have heard no it is fine so I have no idea what to do any comments please. Jim

[Kenneth L. Walters]

I've probably put 2000 cast bullet rounds through my 45-70 in recent years.  I used SAECO bullet #015 cast from linotype.  Weighs right at 300 grains.  I drove it with 13 grains of Unique.  Not a fire breather but a nice, mild recoil (at least in some 45-70's) that is very accurate at the ranges I'm interested in.

Fillers are absolutely necessary with blackpowder cartridges IF the case would otherwise have an air space.  Fillers also use to be recommended in some smokeless loads particularly if you had a large case with a very small powder charge.  This is one reason why the newest Lyman reloading handbook has dropped powders like Unique and replace it with 5744 in some applications.  Not a bad idea I think.

Fillers in smokeless powder cartridges have been known to SIGNIFICANTLY raise pressure levels.  I wouldn't use them even if a reloading manual suggested it.  

I would recommend the Unique charge I mentioned above OR using a more bulky powder like 5744.

[bumble]

I've used 1gr of dacron in the 30-06 for years. With Rx7 and slightly slower powders it helps keep things more uniform. Anymore I find SR4759 gives me all the accuracy I want with no fillers. It saves me alot of time not using fillers and no adverse residue is left on the case or chamber.

[Leftoverdj]

NO!!!!!!!!!!!!!

There are reliable recurring reports of chamber ringing with dacron fiber filler in bottle neck cases.

I've shot a few thousand such rounds myself without a ringed chamber and I stopped before I ringed one. It is important to remember that hving done something without incident is not proof that the incident cannot occur. Having it happen, even once, even to someone else is absolute proof that it can happen.

If I need a filler for a squib load in a bottle neck cartridge from here out, I'm using cotton. Even then, I'm gonna think about it hard first.

Straight walled cases are a far different matter. I generally use cereal fillers in them rather than any form of fiber.

[Blackhawk44]

The danger with fiber fillers like dacron, kapok, even squares of toilet tissue (were recommended, I used to use) is that recoil, handling and sometimes nothing at all can cause the filler to shift ahead of the powder charge, especially if there is air space between filler and bullet, to cause the filler to compress and become a secondary project.  This can cause pressures to skyrocket.  At times and at various stages of the firing cycle anywhere from the chamber to the end of barrel this pressure variation between the filler and bullet can cause one or the other to progress unevenly allowing either to act as a temporary barrel obstruction thereby causing bulging or "ringing".  It cannot be duplicated regularly in the laboratory but does happen there and in the field.  People go for hundreds or thousands of rounds then suddenly something is out of sync and you have slight to major damage and/or some type of injury.  Fillers work with black powder because they are added to create an immovable column of components.  With smokeless, use modern powders and procedures.  Once could be too many.

[ArkyJack]

Guys
I quite agree with Blackhawk44, as I have had just such an experience. I have a Jap T99 action rebarreled with a Springfield `03 barrel and rechambered to .308 Win. With the 2-grv bbl and cast bullets, it was very accurate. Long story short- I was using a tuft of Dacron with 12 grains of RedDot and had used the load for a long time. The problem came without me realizing there was even a problem. The last shot of a string looked to be normal on the target and in recoil, but when I sighted down the barrel I found two joining bulges about 8 inches from the muzzle. All I can attribute it to is the filler doing as Blackhawk44 describes. I no longer use any kind of fillers!! And, bye the way, I have a very loud 16.25" .308, but still shoots good!  My 02
Jack