What causes this? (Neck "Lip")
- Thread starter DocRDS
- Start date
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You explained your process:
Process:
Deprime: Lee Depriming Die
Wet Clean: FART, no pins 3 hours
Dry: Oven @ 200
Size: Hornady Die (no mandrel) Full Length, no bushing
Neck Mandrel: Wilson
Wet Clean: FART, no Pins 1 hour
Dry: Oven @ 200
Load
I may be over-simplifying this but ... do each step then inspect your brass and see when the "case mouth belling" occurs. That then would be your issue. I too have had this issue. I dry tumble. I never saw the issue around tumbling. I did see it when "mandrel-ing". If you follow your process then inspect you will figure out which step is the problem then you can fix it.
Yep, I stopped wet-tumbling my precision cases a while back and the problem completely disappeared (and I haven't seen an SD that wasn't in the single digits since). The fan controller did help, but it didn't eliminate the peened case mouth lips... stopping the wet-tumbling was the answer.
FWIW, wet-tumbling is still my go-to for blaster ammo (9mm & 5.56).
How I setup my mandrel to avoid crushing the neck.
Take a fired piece of brass
Raise in shell holder
Screw down empty mandrel holder until it touches case
Back off one turn
Drop in mandrel
Unscrew until brass no longer lifts mandrel
Back off two turns
Set ring, cap and roll…….
Take a fired piece of brass
Raise in shell holder
Screw down empty mandrel holder until it touches case
Back off one turn
Drop in mandrel
Unscrew until brass no longer lifts mandrel
Back off two turns
Set ring, cap and roll…….
Lose the steel pins if you're using them. If you have a good tumbler and using good brass-cleaner, they're WAY more trouble than they're worth.
If it's not *too* bad, sometimes you can get away with a heavy chamfer and deburr. Otherwise... it's either trim the neck short enough to get rid of the lip (and then chamfer/debur normally), or pitch it in the recycling bin and start over with new brass.
Ya, BRA brass fortunately, and in this case, unfortunately doesn’t grow really at all.
Early on playing with wet tumbling I fell into the trap of leaving my match 308 cases in longer, like I did with a regular vibratory tumbler. Came out with a horrible peened lip.
Something I noticed was that it wasn't just time, but the number/amount of cases and the relative size of the case. 308 peened faster than 223, and 338LM...holy crap.
I have heard of overstuffing a wet tumbler to prevent similar issues. Can’t say I’m knowledgeable, but would that be an option either increasing media or case volume?
Possibly... between the 223 cases having less mass when they tumble against each other, and that I was generally putting as many in there (200+) as I could, they got clean without any apparent damage. 338LM... I generally did in batches of 50, and those things weigh a ton (relatively speaking) banging against each other.
Strangely, I really didn't do anything at all...
While headed there, none of my cases had ever gotten so bad that they wouldn't chamber... so after a couple/few firing/loading cycles all the cases returned to "normal".
FWIW/as an aside, I dry tumble my precision cases using 20-40 grit corn cob blasting media (much finer than the usual corn cob most of us are used to), mainly because it pours out of cases/flash-holes like water, but also because it means I don't have to bang the cases around using a media separator. Sounds super simple, but apparently, not beating the shit out of one's freshly annealed/sized brass leads to better SD/ES numbers lol.
Because I'm a little OCD about removing all the lube post-sizing, I tumble for way longer than I probably have to too, I usually throw them in the tumbler and set the timer to 8 hours and forget about them.
Have you tried squeezing them back to shape with a Lee collet die? That is my usuall go to with mangled case mouths before I just toss them.
I had quite a few that I had to force to chamber, but the rest were manageable, so aim hoping this is the case. Seeing that the 6bra cases literally never grow, I’m hoping the rest we’ll work them selves out as in your case. Got a Berry’s qd-500 in flight as we speak.
I should add that I did (and still do) lightly inside-chamfer my cases every loading cycle... and that probably helped in returning the peened cases to normal (I don't deburr the outside unless it is brand spanking new brass or has been freshly trimmed).
I know many guys skip the chamfer, and under normal circumstances, it may not matter (with brass that hasn't been wet-tumbled and peened), but I only hold the case mouths gently to the cutter/chamfer tool (Hornady Case Prep Duo, RCBS VLD chamfer head) for less than one Mississippi until they whistle (barely removing much material) and figure it can't hurt. YMMV.
The LCD squash method works. I've also done it (to some brass that was really bad back before I figured out it was the wet tumbling).
If you can find a washer that will fit around your case body OD, it will sit on top of your shell holder and cause the LCD to close sooner (without your case mouths sticking out the top like with some LCDs)... squashing your case mouth lips back to straight against its mandrel.
