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SS tumbling- potential damage to case necks?

wolfman

Silver $$ Contributor
I'm one of the dinosaurs who hasn't started annealling yet. I just got a Benchsourse machine, and am all ready to go, but there's a little gremlin on my shoulder saying that I need to make sure my brass is sparkly clean before I start. I'm still using a vibratory cleaner, so my cases do have traces of carbon on the necks. It seems that SS tumbling is the prevailing cleaning method these days, but I can't help but think that all those pins impacting the necks are going to act like tiny little hammers banging up the necks. Am I overthinking this?
 
Your over thinking it. I've SS tumbled many thousands of brass without a single issue. I have started chamfer/debur cases after SS tumbling because the pins will slightly peen the mouth edge. Does that effect anything, not really sure but probably not because I've loaded and shot thousands doing all case prep then SS tumbling and they were all extremely accurate.

I had bought a vibratory tumbler first, barely used it going straight to a wet tumbler. The final results are light years apart.
 
andybrock said:
I would have thought vib cleaning would get brass plenty clean enough for annealing?

It does. You will be fine with your current method of cleaning. I run a brush through the necks after annealing
 
I would give SS tumbleing a try, the results are awesome. I started with a harbor freight rock tumbler for cheap just to make sure i liked the results. The rock tumbler workes great if you are only cleaning 50 or so cases at a time but may want something bigger if doing large quantities. As far as the pins beeting up brass, I have never noticed any adverse effect. Again for less then 75 bucks you can get the HF rock tumbler and try it and make up your mind.
 
thanks gents- I guess the first step is to just start with the resources I have now. It the brass cleaned witht eh current method isn't clean enough, I'll try pins!
 
I think the only thing that you could possibly want to consider with regards to carbon build up in the neck prior to annealing is that the machine will anneal each case for the same amount of time. Now does variable levels of carbon effect how the heat transfers or holds in the case neck? I do not know.
 
I would not use the SS method unless you trim the peened edge off the case mouth otherwise seating pressure will change and/or chambering can be a problem on a tight neck chamber. I have annealed cases after the usual brass cleaning in corn cob/walnut media with no problem
 
The SS pins do not have the mass to damage the case mouths while in a standard tumbler. It's the other cases falling onto one another that damages the case mouths. Try more pins, more water, fewer cases or a slower tumbler if you experience unacceptable damage to the case mouths.
 
Carbon in your necks is your friend. Just nylon brush it. Why introduce 3 or more contaminants to your case internals, pins,soap,and water when the process offers not one iota to the accuracy equation. I don't want to be on the line worrying if a s.s. pin has lodged in the case (it can and does happen)...my concentration has to be solely on the conditions and the target.
BTW, tried it and regretted it.
 
I think everyone will agree that one of the keys to our accuracy obsession is consistency. It would be a reasonable conclusion that if you develop your loads around a consistent interior neck condition, whatever condition that is, that you will have repeatable accuracy. So if you can maintain a certain amount of carbon in the neck consistently, or maintain a clean neck consistently you should have repeatable accuracy.

For me personally its just easier to maintain the same level of clean than maintain the same level of carbon, so thats how I develop my loads, on clean necks.

I only tumble for about 20 minutes so the peening if any is minimal. But I do size the neck, trim if needed and chamfer after tumbling to remove any possible irregularities around the case mouth caused by tumbling.
 
Small batches of brass with large amounts of pins and water, no dinged mouths/necks. It is the brass hitting brass that is damaging the mouths/necks I believe.
 
wolfman,

Just clean the insides of the necks with 4-0 steel wool wrapped around a brush before annealing. Fairly fast and aids in consistency. Clean again with the 4-0 steel wool after annealing, helps with consistent seating force.

HTH,
DocBII
 
The SS pins, by themselves, do not have sufficient mass to dent anything. Otherwise, the entire brass would be all dented up after a wet tumbling session. The peening at the case mouth is caused by the brasses clashing against each other during the tumbling session. The peens are removed when the case is trimmed or chamfered. Peens at the case mouth, to me, are a complete non-issue.

In any event, look at the case mouths of brand new brasses off the shelf. You'll see the same peens at the case mouths as those brasses are tumbled prior to marketing.


Happy Tumbling -

Bayou
 
andybrock said:
I would have thought vib cleaning would get brass plenty clean enough for annealing?

For annealing, yes. If you want totally clean brass that looks like it just came out of the factory, you can't beat the SS Pins and a good tumbler.


For expediency, toss the brass in the vibratory cleanier for just enough time to clean the case so you can see the color change at the shoulder. Anneal then run the brass in the SS Pins with water and dishwashing detergent. Trim the cases when cleaned and sized to square up case mouth.

Do you have to clean the inside of he case? Probably not. But then again, you don't really have to clean your dishes either. Just scrape or scrub off any dried on crud. One local shooter did an extensive study on what the carbon buildup amounted to in his cases. He weighed each case and then cleaned them in an ultrasonic cleaner. Cleaned until the inside of the case was sparkling clean and showed such with his Hawkeye bore scope. The result was that a .308 sized case gained as much as .2 gr of "crud" over several firings. Space that could be used by powder.
 
[/quote]


... One local shooter did an extensive study on what the carbon buildup amounted to in his cases. He weighed each case and then cleaned them in an ultrasonic cleaner. Cleaned until the inside of the case was sparkling clean and showed such with his Hawkeye bore scope. The result was that a .308 sized case gained as much as .2 gr of "crud" over several firings. Space that could be used by powder.
[/quote]

You know I had wondered about that myself but never looked into it. thanks
 

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