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Hey all - first post here, so go easy on me! :)

I've been reloading .308 for a few years now for competitive target rifle, and I recently got a tumbler to clean out my brass. I'm using 250 grams of stainless steel pins (I know this is too few, I'm working on sourcing more) and a high speed rotary tumbler, which I think is the same model as the "thumler's thumbler model B".

I've basically followed the instructions here: http://www.accurateshooter.com/technica ... ess-media/ and have seen fairly good results (mostly clean, but not 100% clean as I don't think I have enough media in there for now). I'm tumbling for between 3-5 hours.

HOWEVER, I have noticed some damage to the case necks. Notably, the necks appear to have "peened" and formed a small lip which isn't visible to the naked eye, but certainly there.

Has anyone had any experience with dealing with this? I've gone through some of the brass with my deburring tool with some success. Would there be any downsides to that? How is my accuracy going to be affected?

I'm thinking in future I'm going to need to massively increase the amount of media I'm running, and decrease time spent in the tumbler to a minimum. Perhaps somewhere around 5lbs of media, and 15-25 minutes of tumbling.

Welcome to the forum.

I tumble for 3 hours with 1kg of stainless media and then trim to length and deburr inside and out and that does the job. I will add that at 8x magnification no burrs are visible and a cotton bud passed up the inside does not catch.

For more media try JD Reloading or 1967Spud as they should have it in stock and I did have a bag tucked away which I can hunt for if you get really stuck.

Welcome to the forum!

I think that steel pins are highly overrated as a cleaning medium, and having tried them binned them. I have heard about damage like dimpling to cases but have never seen it myself.

No doubt one of the steel pins advocates will be better placed to respond than I.

I'm sure that Jon17 from JD reloading in our Innovators and Vendors section sells the pins at a friendly price, so check his thread out.

Why not introduce yourself on the new members forum?

I've just tumbled a mixed load of 50 x 308 and 50 x 300 Blackout, 250g of media seems very low, mine uses the full 5lbs (2.270g). Water added up to about 2" off the top, a good squirt of non-bio washing up liquid and a 1/2 teaspoon of citric acid. From range fired dirty cases to completely shiny clean takes 3 to 4 hours, if I give them a good wash in warm soapy water first then usualy an hour will finish them off nicely.

I've been using mine about 18 months and have tumbled thousands of cases, 308, 300 Blackout, 44 mag and not seen any signs of damage to a single case, and I inspect all my cases after they are cleaned before reloading them.

My routine is to de-prime/full length size, give a quick clean to remove case lube etc, dry, trim to length, chamfer & deburr then into the SS media to get fully cleaned.

Edit. Just took a photo of a 308 and 300 BLK case mouths,

I decap and clean before resizing, never noted any damage to case necks from SS tumbling.

Awesome, so it looks like I'm going to have to change up my tumbling recipe.

What would you guys recommend for dealing with the brass I have already tumbled? It had already been neck resized and deprimed before I put it in there, but I'm thinking I'm probably going to need to:

- Remove the new primers from the batch I primed before I noticed the case neck issue
- Deburr/trim the case mouths
- Full length resize all brass

On a side note: if I remove unspent primers from a case with a universal decapping die, does that damage those primers in any way? My gut instinct says "probably, and don't risk it as they're $5 per 100 primers", but would be curious to know.

Can you post a photo of the case mouth? Difficult to know exactly what it is without seeing it, is it a lip or a wearing away of the edge?.

Full length sizing and trimming to length won't harm the cases, and trimming may remove the problem. One other thing, how many times have you used the cases with the problem? it may be the brass is getting brittle and annealing may help.

I've removed and re-used primers without a problem, obviously make sure you're wearing good safety glasses!.

It's once fired Lapua brass, so I don't think it's a case of the brass being old and/or worn out. I'm at work at the moment, but I will try and take some high res photos when I get home. It's quite hard to see though; the way I've been determining whether there's been any mouth damage is to run my finger nail towards the mouth.

In the absence of a macro lens, this is the best I could do in terms of photographs.

The second view does appear to show a very slight lip on the outer edge of the mouth. Do you have an external chamfer tool you can just gently run around the outside to clean it up?