The .45-120 and Smokeless Powder: Use Filler or Not?

In this video, an attempt is made to determine how much improvement one can expect from using some form of case filler. Keeping all other variables the same, 12 cartridges are loaded using filler and another 12 loaded without. The two sets are then tested in the field using a chronograph.

A number of circumstances can require filling cases with powder taking up far less volume than the case has available. A concern arises from this however: unless filler is used, partial filling may lead to erratic combustion since the powder is free to settle in different positions inside the case when the primer ignites.

A long-used solution is adding some sort of filler to take up the extra space, so the powder is kept in position against the primer. In this video I examine some pros and cons of this method.

The rifle used is a Ruger No. 1, custom-chambered for the buffalo-hunting-era .45-120 cartridge, firing 535 grain cast bullets. Having a large case capacity (due to originally being intended for black powder), if you decide to use smokeless instead, you are going to end up with a lot of unused space since so much less of smokeless is required.

There are conflicting reports about the advisability of using fillers. Some warn that it can result in ringed chambers due to over-pressure if the filler wads up inside. Although not covering every aspect of filler use, this video does look at some of the risks/benefits involved and whether the same concerns apply for all cartridge types and shooting needs.

After the range test, an analysis of the test data is conducted. This portion of the video may also be helpful to some, since techniques for conducting such analysis using statistical methods are shared.

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