The scoop on fillers

[KirkD]

There has been a lot of opinions on fillers. I've used toilet paper filler in a variety of smokeless loads for black powder cartridges for a long time. In the summer edition of the Double Gun & Single Shot Journal, there is an article by Sherman Bell where he tests 14 different kinds of fillers in a rifle chambered for the 450 caliber black powder round, a straight-walled cartridge that fires a 300 grain cast GC bullet at around 1,940 fps. He used strain gauges at the center of the chamber and at the neck where the bullet base is to measure any pressure increase due to filler impact on the bullet base. This is an outstanding article and basically blows away a lot of old wives tales about fillers. Just this article alone was worth the entire year's subscription. I highly recommend it.

[rusty gunns]

Thanks for the heads up on that article.
I have always used corn meal in my bp loads. It fills and allows for compression.
But it sure would be good to know how it tested out. and what other materials are good, as good, or better.

Thanks. I think I'll go "A-looken" for that.

[Ysabel Kid]

Thanks for the info Kirk!

[KirkD]

For those who can't get their hands on the article, he found that different fillers raise the pressure different amounts, though all of them were within the pressure of the original factory cartridge. He tested what I had considered to be a major no-no ..... a card over the smokeless powder greating a gap between the powder/card and the base of the bullet. The strain gauge at the neck recorded a double tap, but the pressure increase at the neck was minor. I'm still not going to do it, although I know from other articles that Bell has written that he seems to do it often. Kapok was the best filler of all. The big thing to remember is that

• 1. the tests were done with a straight walled case that was originally designed for black powder,
  2. He was staying within the ballpark of the original black powder velocities (i.e., not hot-loading it)
  3. He was using a medium speed powder, IMR 4198

I have always recommended that if a fellow is using fillers, that he stay away from fast powders, bottle neck cartridges and steamy loads. Used within the parameters that Bell operates within, all 13 fillers seem to operate well within the safe range and within the pressures of the factory load. Even some fillers that would seem to be dangerous, which I won't mention in case a newbie decides to try them out with a capacity load of Bullseye in a bottle neck, modern smokeless hypermag cartridge. I still say that, although Bell's research shows fillers to be a lot safer than previously thought, fillers should stay within the realm of the experienced reloader who understands how different speed powders, different weight bullets and different case shapes affect pressures.

[Malamute]

Good post, thanks Kirk!

I've used a wad of toilet paper in the 45-70 with 3031 powder at factory level ballistics when noticing a lot of unburned powder in the barrel. I also had a squib that stuck a bullet in the barrel when loading to black powder levels w/ a 300 gr jacketed and 4198. The powder was a clump of fused crud with much loose powder. I started using a square of toilet paper over the powder and the unburned powder went away, and reports were more consistant.

I also use a very small tuft of dacron pillow stuffing over very light loads in various calibers, like 3 grs Uniue in 30-30 w/ a .310 round ball, or 6 1/2 grs Unique w/ round ball in 45-70. Tried them without, but with the fluff the reports are much more constant when used at different angles. Not sure if you can really call that "filler", it doesn't begin to fill the case, just gently hold the powder back by the primer. Been fooling with Red Dot some, it's not supposed to be as position sensitive. I like the very light oads for small game, grouse, snakes, and varmints like skunks in the yard. I slew a mouse that was stealing my bird seed one night with the 30-30 and a round ball load. Worked like a champ.

[geobru]

Thanks for the post Kirk.

There are a few copies available on Ebay if anyone else is interested. Do a search for "Double Gun Journal Summer 2011"

[w30wcf]

Kirk,
That is a great article. Very interesting. It can be seen here...about the 6th post down:
http://forums.accuratereloading.com/eve ... 3971092851

Here's a short synopsis:
Very interesting that PSB (Puff-Lon) which fills the remaining capacity completely, developed the least amount of pressure of all the fillers.

caliber: .450 x 3 1/4" BPE
bullet: 300 gr LBT
powder: 48 grs. 4198
primer: WLR
........................ velocity...psi.........notes
.............no filler: 1,851..... 15,900... hangfires & inconsistent velocities
over powder wad: 1,952..... 21,700... thin wad rubberized cork
..............dacron: 1,940..... 21,400... 12 grs - fills the case
....tuft of dacron: 1,983..... 21,700
...........Puff-Lon: 1,911..... 19,600... 8.5 grs.
Cream Of Wheat: 1,907..... 25,300... 45 grs.
...open cell foam: 1,969..... 21,400
closed cell foam: 1,959..... 21,200
stacked soft felt: 1,941..... 22,300
stacked hard felt: 1,930..... 24,800

.....black powder: 1,812..... 21,600... 120 grs of KIK FFG

w30wcf

[Hobie]

This pretty much supports what I've said all along albeit the conclusion is that fillers are safe rather than that they raise pressures and that is not good. I've always said Pufflon was the best to use if one must use something. That said I've read a lot of Mr. Bells' work and I have a high regard for his attention to detail.

[KirkD]

There are a couple of important points to add:

• 1. None of the 14 fillers exceeded the factory loaded Kynoch ammunition pressures, which fired a 370 grain lead bullet at a velocity of 2002 ft/sec and a pressure of 25,200 psi measured by the strain-gauge mounted at one-inch from the breech face, and a pressure of 26,100 psi at the bullet-base strain-gage position.
  2. The two fillers that gave the highest pressures, Cream of Wheat and stacked felt wads, also gave a velocity that was between 100 and 120 fps faster than the black powder velocity. I recommend that if a fellow is using fillers, that he reduce his powder such that the resulting velocity equals black powder velocities. If Bell had done this, all filler pressures would be even lower than what the factory ammo produces, and several more fillers would be even lower pressure than black powder using Bell's IMR 4198 load.
  3. Some fillers gave even lower pressures and higher velocities than the black powder loads.
  4. If fillers were used to give the factory velocity with a 370 grain bullet, then some pressures would have likely been higher than the factory pressures.
  5. I have used Cream of Wheat filler in my 45-70 list of loads, but I felt that it was generating too much pressure even for black powder velocities. I took apart the cartridges and observed that the compressed COW had solidified into a solid plug that had to be dug out with a unfolded paperclip. What surprises me is that the COW filler gave a pressure that was not ridiculously high in Bell's tests. Perhaps his COW was not compressed. Regardless, although I have used COW filler with no problems, and I know of others who have done likewise for many years, I strongly discourage using it. As for myself, I have ceased using COW filler just to be on safe side of things.

Perhaps a key point deserves its own special mention: Bell held the powder charge constant with all 14 fillers, not the velocity. Even then, most fillers did not exceed black powder pressures by any significant amount even though the velocity was higher. If Bell had held velocity constant with the black powder value (as I usually recommend), pressures would have been significantly lower. However, what Bell did was more important, since a novice reloader may not think to reduce the powder load to compensate for any increases in pressure the filler may give.

One final point: the proper powder/filler combination will actually reduce the pressures lower than black powder if the same velocity and bullet weight is used along with IMR 4198 powder, as Bell's work shows with, for example, cotton.

[cas]

I wonder if he'll do bottlenecks next?

That seems to raise more questions.