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Jan 16, 2024

Test: Case polishing and cleaning methods with the Hornady M

Ground walnut shells and corn cob, ultrasonic baths and small stainless steel

Ground walnut shells and corn cob, ultrasonic baths and small stainless steel pins. You can read and discover here, in the first part, which brass cases cleaning methods or media, wet or dry, have which advantages and disadvantages.

Mirror-bright brass cases. Reloader likes them. Because of the beautiful appearance and the slightly lower resistance when feeding and ejecting. Premium manufacturers therefore nickel-plate cases of their top cartridge lines intended for hunting or sports. Also, their bright casing interior accepts less residue than the relatively rough surface of uncoated brass. For decades, ground walnut shells or corn cob mixed with a polishing agent were the means of choice. But almost only for external use. Inside, on the caked residue from the propellant it does little with case residue. Except that, depending on the color of the polishing agent adhering to the media, the residues also become discolored. For this reason, and otherwise comparable results with Corncob Green, the red Tuf Nut media was ruled out by the testers after the first try. However, the amount of residue that sticks when firing depends on more than just the surface finish of the case. The cartridge chamber dimensions, pressure, powder adhesiveness, clean burning of propellant and primer chemistry are also factors in the degree of fouling.

Short, cylindrical cases accept solid cleaning agents better on the inside than bottleneck cases. Not that media get into these cases poorly. But cleaning takes place by friction, and this requires surface area on which to keep the media moving. Bottleneck cases tend to cause the media to stick. Inside, the media then lack its room to move. For this reason, tumblers should also not be crammed full. The better their filling spins or vibrates, the stronger the cleaning effect. Before tumbling, many reloaders remove primers. The media then often get stuck in the primer pocket, or clog the flashhole. Steel pins can also get jammed there. As an antidote to jamming, pins should be slightly longer than the diameter of the respective primer. In advance, "soft" polishing media clean sufficiently up to mirror finish – depending on the duration. However, in primer pockets as inside cases, residues usually remain unaffected by the media. For handgun cases, all4shooters.com chose the 9mm Luger and .45 ACP, while rifle brass were represented by the .308 Winchester and .45/70.

Small stainless steel pins in rotary tumblers are supposed to clean the outside as well as the inside. This seems credible, especially since the inherently soft stainless steel is not only harder than the residues, but also harder than brass. The polishing, or better grinding ability of the pins is based on the non-deburred edges on their sections. The mass and volume ratio of cleaning ground media to steel pins is striking. The batch of steel pins included in the scope of delivery, weighing around 2,300 g, just covers the bottom of the test tumbler, the Hornady Rotary TBL 100. At around 7.5 kilos, its maximum loading weight has been reached. In addition to the pins, this includes up to three liters of water, or about three kilograms. That leaves a payload of about 2400 grams, an equivalent of a good 400 .45 ACP casings or about 200 .308 Winchester casings. The vibratory tumbler, a Hornady M-1, is inferior to its wet counterpart in terms of payload. Around 1,000 grams of ground media (Corncob Green or Tuf Nut Red) already fill the vibratory tumbler by a good third. But the maximum load weight of the small vibrator is around 2,300 grams (5 lb). That leaves just 250 .45 ACP cases, or a good 100 .308 Winchester cases.

Why, the testers asked themselves, shouldn't the steel pins also prove their cleaning ability in the rotary tumbler when dry? After all, this eliminates the need for tiresome drying. In the rotary tumbler, the steel pins ground for four hours, just as the granules in the vibratory tumbler did on the various test sleeves. The sectional views show how deceptive the beautiful appearance of the granule-tumbled sleeves is. The rather dull-looking, pin-cleaned cases, on the other hand, even show relatively clean primers. Substantial internal cleaning can therefore only be expected with the hard cleaning pins, and takes just as long. Exception: cases whose interior is hardly ever soiled due to the use of "clean" burning propellant and primers matched to it. However, this precondition is not often found, and an almost bare interior (as shown) is gone after the first reloading anyway. A trick to clean cases passably also inside by means of media works, only not for long, with old media. Instead of disposing of it, chrome polish (e.g. Autosol) is added to it. A tablespoon of polish must be finely mixed into the media beforehand, otherwise the casings will clog. Before adding cases to media "tuned" in this way, it is advisable to tumble empty for about ten minutes to detect clumps. After use, the testers only rinsed the pins in an old kitchen sieve and the drum.

The M-1 costs about 100 euro. A sifter for separating the cleaned brass and media is included. Media like corn cob is missing – it costs about 35 euro. The TBL 100 rotary tumbler (about 320 euros) comes with a 2.7 kilogram bag of stainless steel pins. For this, a sifter is missing, and because of the complex construction it costs around 45 euro. So, ready for operation, the M-1 is around 135 euro, the TBL 100 around 365 euro. The maintenance question: 60 to 70 euros are due for 2.7 kilograms of steel pins, but these should last much longer than the ground media, which cost half as much. There is a rule of thumb for its durability: with fresh media, measure the time until the desired cleaning effect occurs. If it takes more than twice as long, the media are rounded and should be replaced. The M-1 draws 26 watts/h, the TBL 100 needs 90 watts/h. But the M-1 holds significantly fewer cases, and the ground media certainly needs changing sooner than the steel pins.

Pins: clean brass, but not bright. Ground media: bright brass, but hardly clean (inside). The cleaning performance of the pins is much higher, but their polishing performance is close to zero. If the cases are to be clean as well as glossy, brass cleaned by pins could still be brought to a high gloss with ground media. Or the follow-up test in part 2 will show whether "wet cleaning methods" can do both.