How It Works: Wet Tumbling Cartridge Brass with Stainless Media
On our main Accurateshooter.com website, you’ll find a comprehensive review of the STM system for cleaning cartridge brass with stainless media. To clean brass with stainless media, start with five pounds of small stainless pins sold by StainlessTumblingMedia.com. Place these along with a gallon of water, a little liquid cleaner, and two pounds of cartridge brass in a rotary tumbler, and run the machine for one to four hours.
CLICK HERE for Stainless Media Brass Cleaning System Review
Forum Member Tests STM System
Our reviewer, Forum member Jason Koplin, purchased the STM media and a new Thumler’s Tumbler. He then tested the STM cleaning procedure on his own brass, including some extremely dirty and tarnished “range pick-up” brass. Jason was thoroughly impressed with how well the STM process worked — as you can see from the “before and after” photos below. Brass which looked like it was ready for the scrap heap was restored to “like-new” appearance. The process works equally well on both rifle brass and pistol brass. Jason observed that one surprise benefit of the STM cleaning procedure is a big reduction in noise. Jason said the water-filled rotary tumbler was much quieter than his vibratory tumblers.
You’ll want to read Jason’s full review which shows more before and after images. The full article features a “how-to” video created by Forum member Cory Dickerson, the young man who pioneered the stainless tumbling process and founded STM. The video shows how to load brass, media, and cleaner solutions into the tumbler, and how to separate media from brass once the tumbling is done.
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Tags: Brass, Cory Dickerson, Jason Koplin, Pins, Stainless Media, STM, Tumbling
STM is like magic, dirty grimy brass goes in, hours later it comes out nearly immaculate (sometimes there are some tiny remnants of residue in the primer pockets, more so on rifle cases that have been reloaded a couple times before cleaning). I wouldn’t dream of going back to the vibratory tumbler again, STM is much more effective and cleaner (and probably safer, no dust to breathe in). I use a cheapie Harbor Freight tumbler, does 2lb of brass at a time which is more than enough to keep up with my shooting.
Forgot to mention, you do want to give your brass a check before you load. On a whim I looked though some primed cases I had ready to load, and two of the pins had wedged themselves against one another inside the case and had to be pried out. I just line them up and look down in all of them with a flashlight before charging.
Seems like sooner or later you would end up with a piece or two of stainless media in the case undetected. Dont think I like the idea.
This method work hardens the case necks and mouths to a degree that cannot be undone by multiple annealings. I blew several primers and extractors before tracing the problem to this. The necks would not let go of the bullets, resulting in a HUGE pressure spike! I called the manufacturer and they were aware of the problem, but apparently not enough so to notify their customers.
Pins stuck in necks is very common in 6.5mm necks. My expensive machine now collects dust.
UPDATE 9/25/17: Very thorough scientific research recently completed by AMP Annealing in New Zealand contradicts the idea of serious hardening. Using sophisticated testing equipment, AMP found the hardening was only a few microns deep and annealing worked just fine. Case-wall hardness was not affected.
EDITOR: We do recommend checking primer pockets for obstructions. Regarding work hardening — we have seen some mild peening of case mouths but have NOT observed the hardening after many cycles. And we are very skeptical of the purported “huge pressure spike” that would blow an extractor. I doubt this can be traced to neck tension — more likely improper loading procedures. Think about it… if the bullet can be seated with a normal die, it is going to release with 50,000 psi.
The inside of necks cleaned this way (and with ultrasound) can get more grippy because the metal surface is cleaned so thoroughly. If you want a smoother release you can brush a little dry lube inside the necks before seating. Alternatively, you can add a couple capfuls of Ballistol to your cleaning solution — that works well.
Would the tumbler with stainless method work to cut grime off of solid brass sikverware, knives, forks, spoons? I collect this stuff, it is solid bronze.
I want an opinion. I polish solid brass dirilyte silverware by hand cutting off grime and tarnush with jewelers rouge and a dremmel tool. Labor intensive!
Do you think I could tumble it with stainless steel to remove grime? Even a few pieces at a time would be easier than dremmel and hand polishing.
Thanks guys.
Kathleen