Tumbling Ammo

[Jersey Devil]

OK......what's the real deal with tumbling ammo? Is it really bad for the loads to do it?? If so, is there an alternative to tumbling ammo in order to polish it???

[RAMMONT]

The best info I've ever found about tumbling loaded ammo was from another gun forum. A guy posted an email that he got from Lapua/Vhitavouria.

Tuesday, August 11, 2009 10:44 AM

"Kevin S Thomas" <[email protected]>

Dear David,

Adam forwarded your inquiry to me, and I'll be happy to answer. The short answer is, no, it's not going to cause a problem, but I do want to cover a few things just to be safe. The slightly longer answer is yes, it could. Tumbling of loaded ammunition is a common practice for ammo manufacturers, and it's done all the time. The key is, they don't do it for very long; usually nothing more than required to remove any traces of lube from the loaded ammunition, or whatever else may need to be accomplished. I normally do this with large lots of pistol ammunition if I've bulk loaded them on a progressive press. Again, the key is, they're run for a very short period of time, never more than 10 minutes. You're obviously familiar with powder "construction" and the application of deterrent coatings such as graphite or dinitrotoluene (DNT), and I assume your concern stems from the possible removal of or damage to this coating. Actually, this is precisely how many of these coatings are applied to begin with, and the powder goes through several tumblings during its production. In short, damaging it via this same process is fairly unlikely, especially once the powder is contained in a loaded cartridge.

This said, anything can be overdone. Tumbling cartridges for an excessive length of time, or in too vigorous a tumbler could be detrimental. I can't hazard a guess as to how long this may take, as I suspect there will be several variables coming into play. The bottom line is, minimum tumbling, in as gentle a process as will accomplish the task. For my own loadings, as I said before, I use ten minutes as my own personal maximum, in a vibratory tumbler. Loaded cartridges will likely see much more severe treatment than this in the field (bouncing around in SUVs off road, etc.) so I personally regard this as an acceptable limit.

Longer tumbling times and/or exceptionally rough tumbling methods could, theoretically, create problems. These may relate to the deterrent coatings, or to the possibility of external damage . The potential for accidental ignition via a primer being impacted by an FMJ, that sort of thing. I've never heard of such an occurrence, but I wouldn't discount it, either. The key here is some moderation and common sense.

I hope this answers your concerns, but if you'd like to address anything more specifically, I'd be happy to discuss this with you further. Please feel free to contact us again, anytime. As always, we're more than happy to be of service.

Sincerely,
Kevin Thomas
Lapua USA

The same poster also contacted other powder manufacturers and asked about their recommendations about tumbling loaded ammo, the answers included warning about the powder itself decomposing, the coatings rubbing off, and the primers becoming damaged. None of them actually produced technical data from actual testing so we don't know any details but I suspect that how the powder reacts varies according to what powder was used (flake, spherical, stick, etc.) and how much space the powder takes up inside the case. As for the primer, I'd bet that the most common problem would be how powder dust or broken particles of powder might become packed inside the flash hole or get down in to the primer itself through the flash hole.

I don't use a tumbler any more, I use an ultrasonic cleaner and I clean my cases after I finish with my last case prep step. I don't worry too much about the cases being less than perfect because I want the case to stick to the chamber walls when it's fired and the smoother the case finish the less friction there will be between the case and the chamber walls. As long as I don't have gross fouling of the case (rust, dirt, etc.) I don't worry too much about the looks of the case, my ultrasonic cleaner leaves the cases nice and shiny so it's not much of an issue anyways.

[Jersey Devil]

Rick,
That's a really great post, and thanks for taking the time to quote the email from Kevin Thomas as well as add your valuable advice and experience.

I have quite a few rounds that have a lot of dirt on the cases, and that's what I'd like to remove. Wiping each cartridge down individually would take a really long time. I think I will try tumbling a handful of rounds for about 5 minutes and see how they come out.

What do you think about that?

Thanks again,
---Brian

[Phil McGrath]

Rick,
That's a really great post, and thanks for taking the time to quote the email from Kevin Thomas as well as add your valuable advice and experience.

I have quite a few rounds that have a lot of dirt on the cases, and that's what I'd like to remove. Wiping each cartridge down individually would take a really long time. I think I will try tumbling a handful of rounds for about 5 minutes and see how they come out.

What do you think about that?

Thanks again,
---Brian

It really depends on how dirty your ammo is, if your worried rub off what you can and then finish off in a tumbler say 5-10min. Personally when I finish reloading I wipe off what I can and then Its a quick run in my tumbler just long enough too remove what case lube remains. I don't use a globs of lube just enough too resize and even with that little amount it still takes about 15min. My tumbler is pretty old so it doesn't wiggle/jiggle as well as it once did.

[RAMMONT]

I agree with Phil, I don't see where a 5 or 10 minutes would do any harm.

[Jersey Devil]

Very cool. Thanks guys!!

[m14brian]

My concern here is for rifle ammo, if somebody tumbled them too long could powder that is long and shaped like rods break and burn unevenly and create unsafe pressures, or is that overthinking it?
m14brian

[RAMMONT]

As long as we are talking about 10 minutes or thereabouts I doubt that it makes any difference. It's not like the powder can move all that much within the case so I can't imagine that the granules would have enough momentum to cause them to shatter. I imagine that any granules that were damaged during manufacture might break but that's probably not a very high percentage of the total number of granules in the case. I've read that broken granules can create higher pressure because of the larger surface area but if the total number of damaged granules is really low I doubt if the pressure increase would be outside the normal variation in pressures.

[bruce]

Interesting thread. Especially appreciate the Lapua quote. Have always tumbled brass, but not loaded ammo. Never really thought about the need of the case to stick to the chamber during firing. Once upon a time, polished my brass with Semichrome polish before loading. Back then, loaded .30-06 hot enough to be suitable for anything on the sub-continent of Africa. Remington 700 must have been fairly strong. Never had a problem. Very easy extraction. Nowadays... figure most stuff will lie down and give up the ghost if given a dose of 150-165 BTSP at about 2800 fps. So far, 100% effective. In my M-1's, typically use HXP ball... M-2 or AP. Sometimes little less than perfectly clean looking. If 10 minutes in a tumbler will clean it up, fine. Probably make it run a little better in my M-1's, and of course it will not get my hands so dirty! Sincerely. bruce.

[Jersey Devil]

Stupid question, but if I were to tumble some ammo for 5 minutes or so would I tumble it using dry or wet media?

[RAMMONT]

I don't know about the M1 but I know that the M14 blueprints show that the chamber is specified to have a surface finish of 62 micro-inches (if I remember correctly) which means that after it's been reamed they don't recommend lapping or polishing in any way (lapping produces a typical finish of 8 to 16 micro-inches). The rougher finish (62 micro-inches) serves two functions, it makes mass manufacturing of the barrel easier because there isn't any time consuming hand polishing or lapping required and it helps to ensure that the case sticks to the chamber walls when it (the case) obturates (expands during firing and blocks the combustion gasses from escaping in to the receiver). Polishing the brass and giving it a smoother finish isn't going to cause any real problems in the chamber since the chamber is designed to help the case obturate but I figure that any small amount of case discoloring (I'm not talking about rust or actual fouling buildup of dirt, carbon, etc.) wont hurt anything. I do though, believe that it's not good to have any lubricant on the case after you load it because the lube makes obturation harder to accomplish. That applies to both pistol and rifle cartridges. It's probably not as critical with some pistol cartridges but I'm not educated enough to know which would be OK and which wouldn't so I just remove the lube on all of them.

I just double checked my blueprint data. The M14 shows a surface finish of 63 micro-inches for some features of the chamber and 32 for others. The M1 shows 32 for everything in the chamber up to the rifling.

[RAMMONT]

I'd recommend dry only because I just don't know how well the case is sealed at the primer and the neck. I'd assume that liquid wouldn't penetrate in to the case (with 5 or 10 minutes of tumbling time) but why take the chance. If you used some sort of sealer on the primer and the bullet/neck then I'd guess that it wouldn't matter.

[Jersey Devil]

Great info, as always, RAMMONT. Thanks for your advice!!

[TJT]

I don't tumble loaded ammo. All of the lube from sizing is washed off using Dawn dish detergent. After the cases are dried, and all other operations completed, then they go in the final polish/tumble using corn cob media. It's small enough that the flash hole does not get plugged up as with walnut shells. They are now ready to load.
Jon

[Phil McGrath]

Truth be known, like most everyone else my brass gets tumbled for hours if need be before they are run threw my dies, being a cheap SOB I use a 50/50 blend of walnut/lizard litter and white rice that I steal from the wife's kitchen reason being I hate too eat rice and what amount I swipe is that much less I have too choke down later on. When I'm satisfied with there finish and I do use a small amount of brass polish there then prepped and loaded up. I don't deprime before cleaning/tumbling so there is no worry about plugged flash holes. After there loaded up I wipe them off with a towel and if any case lube is still present a quick 10-15min run back in the tumbler. Latex gloves are used too remove them from the tumbler and there boxed up in ammo bins.

Another reason for the rice is less dust is made, but I also drop in a used drier sheet. This makes for near 100% dust control.

[m14brian]

Anybody use stainless steel rod media?
m14brian