Wet tumbling with stainless pins are causing a burr on insidevof my case mouth.

I use a small rock tumbler from Harbor freight. I'm not loading large amounts of brass so I don't see this on the case mouths. interesting though.
 
I had some new brass that was trimmed and chamfered on a v3 case trimmer. While it looked like it was properly chamfered I was getting primer pockets blowing out. Trying to figure out why I had pressure, I noticed the burr when inspecting the brass. Taking any small tool or knife point when I run it up the case mouth on the inside it was catching and hanging up. After removing the burrs and re testing, all my problems went away. I started inspecting brass right after tumbling and found the burr came back. That is why I'm chamfering every time. To make a long explanation shorter that was my conclusion that the wet tumbler and stainless pins caused the problem.
That's why I chamfer/debur all brass, even virgin brass after running through sizing die.
 
Alex Wheeler did some significant testing and research with "Wet Tumbling" and stainless pins and came to the conclusion that it's not for him. Was causing too many issues with the "necks" of his brass and consistency. There's a post somewhere in here on it and was very interesting. Personally I just wash my brass in warm dish soap water, then tumble in cob or Walnut shell media and has served me well. My brass doesn't look brand new but it doesn't need to.
 
The easiest way to reduce "peening" of the case mouths is to use more stainless media. If you normally use 5 lbs of pins, try using 10 lbs or more (I think I use about 15 lbs). It won't eliminate the problem but should significantly reduce it. Also fill the tumbler completely (or nearly so) with cleaning solution. Time of tumbling may have some effect also but that for me is the last thing to adjust.
Btw my tumbler is the Frankford arsenal large one.
 
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I have gotten neck dings/burrs from wet SS tumbling. I use only pins in one primer size, and shapes mix in the other (can't remember which right now, but IIRC shapes get stuck in SRPs), and they seem to do about the same if I leave the cases in for awhile. Like @ericbc7 i use a lot of media and fill the container completely.

My solution was clean only when necessary, and even then clean as little as possible. Normally I use rice in a vibratory because that seems to be the most mild method I've come across.

I chamfer and debur every single piece of brass before loading. I did that even when i dry tumbled. Who doesn't?
👋 I don't. I also don't overly clean brass every firing either, and rarely trim. About the only exception is using a Giraud to trim and chamfer some varmint/benchrest cases at the same time. If a case mouth isn't bent while extracting or doesn't land on concrete, usually they stay in very good shape.
 
I quit wet tumbling because of the extent of damage to case mouths. I had to take off too much material in subsequent deburring to get rid of the bell shaped damage to case mouths. Now I just I clean cases in a vibratory tumbler with dry medium.

I still touch up the trim, chamfer and deburr with a 3-in-1 carbide cutter every reloading, but need to remove hardly any material.
 
You are getting pressure from not lubing your bullets when seating them in brass that has been cleaned with the pins. The bullets can gall to the neck and will increase pressure. I stopped using the wet tumbling with pins a long time ago as there are too many other problems induced from the pins and the brass too clean.
 
I used to wet tumble with ss pins. Recently tried Brass Juice with no pins and can say without a doubt they are as clean as tumbling with pins. Won't ever use pins again.
I understand and have seen this mentioned online, but I have a ton of range pickup pistol brass, and I definitely use pins with that. Nothing gets that type of brass cleaner. I don't use the FA pins that came with the large FA tumbler, but some better aftermarket ones that are a bit smoother and a fraction longer and I haven't had them get stuck in primer pockets or inside cases. Can't recall the brand. I use a small amount of Armor All Car Wash & Wax and just 1/4 tsp of Lemishine and run them for an hour and they look great. For rifle brass if they've started clean I'll usually just dry tumble in corn cob media with Dillon Rapid Polish. I did have about 600 cases of once fired Lake City M2 ball brass that had been sitting for about 55 years and that definitely got the full wet tumble with pins treatment the first time.

I've seen some shooters online swear that they get better ES and SD performance by dry tumbling only, but I use an expander mandrel (with Redding dry lube if it's a steel mandrel, but not if it's TiNi) after FL sizing, then trim, chamfer, debur, then a case neck brush with dry lube before bullet seating, so cleaning the brass wet or dry doesn't matter to me. Some F-Class guys are using Neolube inside the case neck before bullet seating to minimize seating force, but a dry lube works for me.

For wet tumbling with pins I think the key is not to do it too long. My older FA has a 90 minute max, but the newest version has a "no limit" setting.

I already have enough stuff bought for wet of dry tumbling so buying yet another thing (Brass Juice) when I can make my own solution doesn't appeal to me. I already have some Lyman brass cleaner I made up years ago from concentrate to use with a ultrasonic cleaner if anyone remembers those, but the Armor All Wash & Wax and Lemishine seems to be working great, and a bottle of each will last me the rest of my life.
 
You are getting pressure from not lubing your bullets when seating them in brass that has been cleaned with the pins. The bullets can gall to the neck and will increase pressure. I stopped using the wet tumbling with pins a long time ago as there are too many other problems induced from the pins and the brass too clean.
I wouldn't consider lubing the bullets, but the inside of the case. Using Redding dry lube or Neolube works.
 
For wet tumbling with pins I think the key is not to do it too long. My older FA has a 90 minute max, but the newest version has a "no limit" setting.
Yes. I got a cheap auto-shut off timer that you hit a button for 10-20-30-60m options and it starts a timer:
 
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