Filler Wad or Not?

[Ray B]

Reviewing load data for several cartridges, particularly the over 40 ones, loads can be grouped into two categories: those that indicate use of a filler and those that don't. Comparing same cartridge loads the ones with a filler have a load density of less than 80%. Those with no filler are more than 80%. There are two reasons generally given for fillers: 1. it keeps the powder tight against the primer so that the ignition is uniform. 2. The filler acts as a shock absorber between the accelerating powder column and the bullet base.
If the above is correct then I wonder about those loads of 81% density- the load doesn't call for a filler- so does that mean that the case is full enough so that it results in uniform ignition? also, is the distance from the powder column to bullet base so short that there is almost immediate contact before the powder charge has achieved significant acceleration? Would there be any benefit to custom fitting a filler so that the load was 100% density (a goal of many benchrest shooters)?

 

[JimP]

I always used a filler for lighter loads. Even with 80% fill you can see a difference if you take a sharp enough downslope shot where the powder has moved away from the primer.

I bought a dacron filled pillow around 50 years ago to use as a filler and still have 3/4's of it left. I believe that some will even use cornmeal to take up space.

 

[grand veneur]

A very controversial topic. The filling density is one thing, the burning rate of the powder is another. You also have to consider the cartridge and its caliber, as well as the purposes for which it is used, hunting or precision shooting. A load density of 100% without powder compression is ideal and can be achieved with many cartridges by choosing the right powder, but certainly not with all. It may be possible to notice something with a load density of less than 100, but I am not sure whether that is relevant for hunting. I never worry about a load density up to 70%, since in all cases by such loads I use fast burning powder. Lower than 70%, I consider using a different type of powder that will provide me with a better load density, because cartridges with bottle-neck cases are not easy to load with a filler. The problem arises especially with cartridges of greater calibers where, due to the capacity of the case, one cannot always choose a powder that offers an optimal 100% filling, as far as one wants to maintain the performance of the cartridge. Furthermore, due to the primer used, there can be a problem of igniting a very large amount of slow burning powder. In the end I only had to use filler wads when loading the cartridges 577 Nitro Express and 600 Nitro Express because all the problems I mentioned above were there. Due to the slightly conical shape of their case, both cartridge mentioned are relatively easy to load with a filler wad. With bottle-neck big bore cartridges, the problem is certainly different and the choice of the filler must be carefully considered.