Wednesday, July 22, 2009

Drop Tube

Sometimes, when we're reloading we find a particular load combination that requires a compressed load. Compressed loads occur when the powder intrudes on the space where the bullet comes into contact with the powder charge. These loads are not necessarily unsafe and can be found in most reloading manuals with a small "C" after the load data.

I guess it's time for the standard reloading disclaimer:
Reloading and use of reloaded ammunition can be hazardous. Read up on safety procedures and seek competent instruction. Wear safety equipment such as eyeshield and gloves. The author assumes no liability for other persons who may use methods or data in this article. PawPaw assumes no liability for persons who may use methods or data in this article. We are all adults here, and are expected to know the dangers inherent in our hobby. If you are a minor, please talk with a responsible adult before enjoying the hobby of reloading. This is an advanced reloading technique and should be used with a full knowledge of the dangers and risk inherent in reloading. If you can't follow directions or understand the cautions, then you should click here.
Now that we've read the cautions, it's time to talk about drop tubes. This is an old technique that the black-powder shooters used to add powder to a load. They're sold commercially and can be used for black powder and smokeless powder.

Drop tubes don't compress the powder, but they align the granules and assist in more closely filling the available case capacity. I don't like compressing loads, I feel that the powder was manufactured to perform a certain way, and crushing granules is probably a bad idea. So, drop tubes are useful to settle the powder into the case.

At some point last year, I decided that I needed a drop tube to occasionally load a particular load in .30-06. The published load data told me that the load, as it approached the upper levels, would require compressed powder.

I don't like compressing powder granules, So, I decided to make a drop tube. My considerations were that it must be of non-sparking material because any build-up of static electricity can be bad juju when using gunpowder. Sparks are bad. I hied myself down to the local hardware store and purchased a small piece of copper pipe and some step-up fittings. A few minutes with a soldering torch and I had cobbled together a serviceable drop tube, an extended funnel. I camfered the lower end with a VLD camfer tool and aggressively camfered the tube so that it would fit snugly on brass. Total time of construction was about one hour. Total cost was well under $10.00 US.

A picture is worth a thousand words.



Again, I'm not recommending that you exceed the load recommendations from the various powder or bullet manufacturers. But, a drop tube is a very good addition to the advanced reloader's bench.

3 comments:

Rivrdog said...

I wonder if you couldn't achieve the same result (of reducing the space between powder granules) by simply vibrating the shell as the powder is dropped.

Any sort of vibrating equipment would probably work, but experimentation would revel which frequencies and amplitudes of vibration would work the best.

Pawpaw said...

Junior drums his fingers on the loading block to settle powder into the case.

There's more than one way to skin a cat.

calinb said...

Any chance that compressed .30-06 load was a Nosler RL22 load? I tested all three loads (light, medium, max) from the Nosler databook for their 165gr Accubond. All but the lightest load is compressed (105% for the max load) and, as indicated in the Nosler data, my testing revealed the max load is far less accurate than the other two loads. Shooting seated, I got 1.2", 1.4" and nearly 2.5" groups for light through max loadings from my Win M70. I went with the medium load and shot my elk but I'm interested in trying a drop tube to, hopefully, get some of the impressive velocity published without losing accuracy.

Thanks!