Dacron filler: how much is enough?

[Chuck Perry]

I picked up a pound of 2400 to try with cast bullets in my 45-70 Contender. Looking through my Lyman Cast Manual, it recommends the use of a Dacron wad. I just read thru a ton of previous posts here on THR about the subject, but have been left with this one question: how much is enough? Should one be filling the entire void between the base of the bullet and the powder, or using just a "tuft/pinch/bit" to hold the powder in place? I'd really like to avoid a bulged barrel!
I have read various opionions on whether the filler is really necessary. I intend to try some loads without it first, but want to do some research in the event I find it necessary.

 

[Legionnaire]

Sorry, can't help. Tagging to watch for replies to this interesting question!

 

[Centaur 1]

My understanding is that you don't want to pack it in, but rather just gently push in the fluffed dacron. I was shooting my 30-30 yesterday with a plinking load that uses 6 grains of Bullseye. On the recomendation of someone on a cast boolit forum that I belong to, I used a 1 grain tuft of dacron. The dacron supposedly works as a poor man's gas check.

 

[rcmodel]

Just use a tuft big enough to stay in place over the powder when you push it down on top of it.

No worry about a bore obstruction with Dacron, as it all burn up when the powder lites off.

That is why it is far superior to cotton balls, etc.

rc

 

[Chuck Perry]

Ok. So, the bore bulge issue only comes into play when unburnt filler is present in the bore and creates an obstruction? That will be easy enough to detect in the Contender.
Some of the posts I read made it seem like you could also bulge the chamber as the dacron wad could act like a secondary projectile?

 

[BruceB]

Folks;

This topic sees a LOT of play over at Cast Boolits. A search over there will yield a week's worth of reading!

I use the bagged dacron ("polyester fiberfill") as available in sewing centers. A bag will last a very long time.

When the powder charge is selected, I try to visualize the space left in the case, and pull off tufts of dacron which are somewhat larger than that airspace. I don't bother weighing the tufts. The tuft is pushed into the case with some sort of blunt tool, usually a square-nosed screwdriver. I stop pushing as soon as the tool contacts the powder.

If the tuft is correctly-sized, there should still be a bit of dacron outside the case mouth. This remnant is tucked just inside the mouth, and seating the bullet finishes the installation. NO heavy compression, NO empty airspace! We're speaking of a VERY low-density filler. Even in the .416 Rigby, a 120-grain+ capacity case, my tufts only weigh a grain or so with a 50-grain powder charge. The entire volume above the charge should be occupied by dacron, but not a tightly-packed mass of the stuff.

I've fired many thousands of rifle rounds so-loaded, with no problems at all. Direct comparisons between otherwise-identical rounds(with/without dacron) in MOST cases show slightly-higher velocity, slightly lower extreme spreads in speed, and often better accuracy with dacron. Occasionally, the sacron-filled load will deliver worse accuracy, so it's not a magic elixir or cure-all. It's a useful tool, and worth trying, particularly if ignition is a bit spotty or unburned powder is a problem.

I suppose it offers a bit of protection to the bullet base, but I doubt it can be classed as a substitute for a gascheck. The dacron does NOT burn or melt....I regularly recover remnants on my bench or the ground. Individual strands seem to break up, but even after hundreds of consecutive rounds the gas systems of my autoloading rifles are free of any sign of melted dacron.

 

[Grumulkin]

I highly doubt filler is necessary. If the powder was of such low volume compared to case volume that I was concerned about ignition, I would find a different powder.

 

[Jim Watson]

I like Bruce B's approach, it agrees with Ross Seyfried's use of fibre fillers in big express rifle cartridges. A tuft tamped down on the powder getting a running start at the bullet base has been suspected of "ringing" chambers.

But I would try it without any filler first. Safer and simpler if it gives acceptable accuracy.

 

[EddieNFL]

I pretty much follow Bruce's procedures. I use a wooden dowel to poke it in the case.

 

[Chuck Perry]

Good stuff, thanks for the post BruceB.

 

[BruceB]

Grumulkin:

I left out a vital point: ALL my use of dacron has been with cast bullets. I've never used the stuff with jacketed bullets, and I believe you're absolutely correct that the filler isn't needed......with jacketed bullets.

As I'm overly-fond of saying in some places, "Cast bullets are DIFFERENT." My consumption is well up into the thousands-per-year bracket, and it's a fascinating sideline for hndloaders,

Jacketed bullets create much greater friction than an equivalent-weight cast bullet, and the resistance practically ensures good ignition.

Thanks for reminding me to mention this vital point.