Fix belling of lip

UndFrm · Feb 3, 2025

I have approx 20 cases that have a belling on the lip. While I am still trying to figure out the cause (likely too long case size or too much neck tension from what I read), is there a way to fix these cases so I can still use them or chucking them is the only option now? I have tried chamfering the lip but it still wouldn't chamber.
Also, these cases have a slight "dent/chipping" at the lip, likely due to me applying more pressure than needs to in an attempt to close the bolt (it didn't close).

The size difference is as follows:
.268 at the neck
.271 at the bell

The cases are Alpha 6mm Dasher

Thank you

918v · Feb 3, 2025

When you seat a bullet most of the bell will go away. I too hate the bell. The cause is the radius on the bottom of the busing.

UndFrm · Feb 3, 2025

918v said:
When you seat a bullet most of the bell will go away. I too hate the bell. The cause is the radius on the bottom of the busing.

When you say bottom of the bushing, is that the bushing in your sizing die?
I am using a Forster FL die, with no bushing.

hewlett260 · Feb 3, 2025

Can we get some specifics on your setup and process? You mentioned your die, but what press and other equipment are you using? How you set your die and a little more info could help identify the cause as well as help others not run into this issue

memilanuk · Feb 3, 2025

Case OAL? Are the ones that are 'belled' measurably longer than the ones that aren't?

918v · Feb 3, 2025

UndFrm said:
When you say bottom of the bushing, is that the bushing in your sizing die?
I am using a Forster FL die, with no bushing.

Then it’s the radius at the bottom of the neck in the die.

UndFrm · Feb 3, 2025

hewlett260 said:
Can we get some specifics on your setup and process? You mentioned your die, but what press and other equipment are you using? How you set your die and a little more info could help identify the cause as well as help others not run into this issue

I am using a Lee value turret as a single stage, with Forster FL sizing (no bushing die) and then a Forster micrometer seating die. I do wash and anneal after every firing.
Because it's a no bushing die, the neck tension comes down to 7 thou which I do understand is a too high.
For the FL die setup, I lowered the ram until touch and backed out a quarter turn. From here, I kept adjusting "in" until it's pushing the shoulder back 2 thousands. I verified that it's consistently pushing 2 thousands now.

I ran into this issue only after 7 firings of the brass while the die setup wasn't changed. I do verify the length of the case after each firing and FL sizing and then trim (and chamfer, debur) if it's over 1.535, then seat the projectile.

memilanuk · Feb 3, 2025

If they aren't belled when they go in the die, then they're hitting something *inside* the die. There's a pretty limited number of options for what they could be contacting. And since it's only *some* of the cases, not all, you need to figure out what's different about those particular cases.

UndFrm said:
I do wash and anneal after every firing.

That's the other usual suspect right there - if you're running the cases in a rotary tumbler for washing, it's pretty easy to roll the edge of the mouths and get pretty much *exactly* what you're seeing. The odd bit is that you say it's only *some* of the cases showing that kind of damage. Usually it's most/all of the batch, once it starts.

918v · Feb 3, 2025

Look at his pic. The neck is belled. Thats a different condition than case mouth peening.

memilanuk · Feb 3, 2025

918v said:
Look at his pic. The neck is belled. Thats a different condition than case mouth peening.

Some of mine curled back like that .

918v · Feb 3, 2025

memilanuk said:
Some of mine curled back like that .

That’s not possible

memilanuk · Feb 3, 2025

Believe what you want

CK1.0 · Feb 3, 2025

Looks exactly like what I’ve seen from cases being wet-tumbled.

You can fix the cases with a Lee Collet die and a washer. You slip the washer around the case so it’ll drop down to the shell holder, and then the washer will hold the collet die up a bit so the case mouth stays inside the die body while you squash the case mouths back to normal against the collet die’s mandrel.

hewlett260 · Feb 4, 2025

I can't comment to the people cleaning their brass and the various methods.

If you were using a bushing die I would recommend removing the decapping assembly from the die and see if it still happens.

I do agree with the above poster that something inside the die is likely causing it. When was the last time you cleaned the inside of your die?

A build up of lube being pushed to the top and gumming up was my first thought.

My second thought could be the same reason I stopped using RCBS dies 18 years ago where my 300 WM FL sizing die wasn't cut long enough for the case neck/mouth. All kinds of whacky shit happened to my brass on the 3rd resizing. After measuring everything we found out the neck area about 2/3 up from the shoulder wasn't cut properly, likely due to a worn out reamer. A similar experience with a 7mm Weatherby die and a 308 die caused my switch away from both RCBS and standard sizing dies.

diggler1833 · Feb 4, 2025

I have had this happen in one bushing die before, as well as one F/L die. I too verified with a caliper.

I'm not saying that I know what causes it, other than my brass was not excessively long (less than SAAMI max). What I will say is that running it over a mandrel at .002 under bullet diameter fixed my issue (retuned the neck to a consistent diameter throughout, thereby removing the bell) and I had zero issues chambering and good accuracy afterwards.

The bell part is actually the proper diameter, the base of the neck was oversized by several thousandths.

Ironically, both of mine were with 7mms.

I've cleaned 50 - 100K pieces of rifle brass in my life, and never had that happen in any kind of tumbler, wet or dry.

Perhaps somebody will chime in who knows what causes it. I chalked mine up to the die (which were properly set up according to the instructions).

morganlamprecht · Feb 4, 2025

diggler1833 said:
I have had this happen in one bushing die before, as well as one F/L die. I too verified with a caliper.

I'm not saying that I know what causes it, other than my brass was not excessively long (less than SAAMI max). What I will say is that running it over a mandrel at .002 under bullet diameter fixed my issue (retuned the neck to a consistent diameter throughout, thereby removing the bell) and I had zero issues chambering and good accuracy afterwards.

The bell part is actually the proper diameter, the base of the neck was oversized by several thousandths.

Ironically, both of mine were with 7mms.

I've cleaned 50 - 100K pieces of rifle brass in my life, and never had that happen in any kind of tumbler, wet or dry.

Perhaps somebody will chime in who knows what causes it. I chalked mine up to the die (which were properly set up according to the instructions).

its from sizing your brass down too far in one shot

and yes, the bell is the part that actually matches the bushing diameter, the neck overshoots and doesnt spring back

unless you have a custom made, cant be fixed with a standard full length sizing dies...unless you mandrel/leave the expander ball in

with busing sizing dies, you can step it down .002-004 (likely depends on brass type/hardness) at a time and it will go away...or like you did, just run it over a mandrel

iirc something more than like .004 at a time can cause it...ive posted it here before, but idk if i can find the post

morganlamprecht · Feb 4, 2025

(embarrassing) question about Redding bushing dies - .004" discrepancy. Annealing?

I'm embarrassed I'm so confused about this; hopefully somebody can help me understand. I'm reloading Hornady Match 308 brass. 7th firing, tumbled clean with corn cob, annealed on AMP. Necks not turned. Shot out of a DT barrel, standard chamber. I'm using .332 bushing (I haven't reloaded .308 for...

www.snipershide.com

and later in post #15 from this same thread someone posted Redding tech help covering the same issue

Doghed · Feb 4, 2025

I have a very roomy factory 308 chamber that produces a .344 neck OD on fired brass. Trying to push that into a .332 bushing is too much movement for one operation in my experience. I switched to a two step process where I run them into a .338 bushing first. Then drop in the .332 for the final step before the .306 mandrel.
This works great for me.

Bigfatcock · Feb 4, 2025

Fl sizing dies often have the capability to bell the case neck to allow the seating of flat based bullets. Screw the sizing stem out a couple turns.

Most standard seating dies also have the capability to remove the bell on seating. They can also give a roll crimp. Lee sells FCD that provide a nice collet crimp.

ETA:If your cases aren’t trimmed to a consistent length, then you’ll end up with issues where some go farther into the die than others. That’s why some will have a bell and some won’t. Consistency requires consistency throughout the entire process.

memilanuk · Feb 4, 2025

morganlamprecht said:
the bell is the part that actually matches the bushing diameter, the neck overshoots and doesnt spring back

Except that it isn't, in this case. 0.268 seems like it'd be about what you'd normally get after sizing down, minus a little for spring back. 0.271 before seating would give almost zero neck tension, depending on the neck thickness.

morganlamprecht said:
its from sizing your brass down too far in one shot

I've ran into this myself a few times... but I never had it bell the mouth. It's annoying AF. Made the necks undersized, yes. But there's no connection between that, and the mouth magically belling back out.

diggler1833 · Feb 4, 2025

morganlamprecht said:
its from sizing your brass down too far in one shot

and yes, the bell is the part that actually matches the bushing diameter, the neck overshoots and doesnt spring back

unless you have a custom made, cant be fixed with a standard full length sizing dies...unless you mandrel/leave the expander ball in

with busing sizing dies, you can step it down .002-004 (likely depends on brass type/hardness) at a time and it will go away...or like you did, just run it over a mandrel

iirc something more than like .004 at a time can cause it...ive posted it here before, but idk if i can find the post

I agree completely on the bushing die. It also did it on the F/L sizing die too with the expander ball...which is why I just chalked that die up to being bad. We're talking about .006 difference between the base of the neck and the mouth where the bell was.

It could also be due to having bought once-fired brass in that particular instance (with the F/L die) that was fired in an extremely "roomy" chamber.

Either way, the .002 mandrel fixed my problem.

918v · Feb 4, 2025

If you neck size the case with an older (pre-2015) Lee collet die and bump the shoulder with a body die then you don’t get that neck funnel bell shit, even if you stainless tumble afterwards.

Bigfatcock · Feb 4, 2025

I SS pin tumbled over 5 tons of brass when I sold brass. I had case mouth peening, but never belled case mouths from the process.

918v · Feb 4, 2025

Bigfatcock said:
I SS pin tumbled over 5 tons of brass when I sold brass. I had case mouth peening, but never belled case mouths from the process.

That’s cuz you obey the laws of physics.

UndFrm · Feb 4, 2025

I do clean them with SS pins and I had recently upped the time from 45-60mins to 90 mins. Not sure if this is the cause of peening and then the peening resulting in this after sizing. But will dial back the cleaning time for one.
Regarding the die, I probably cleaned it maybe 2 months ago and will clean it again now. Also, as some have mentioned, sizing too much can cause this and I know that the neck is being sized more than the 2 thousands, so that's a possibility too.

Will look into a mandrel to possibly fix this, and getting a bushing die for sizing.

Thank you

morganlamprecht · Feb 4, 2025

memilanuk said:
Except that it isn't, in this case. 0.268 seems like it'd be about what you'd normally get after sizing down, minus a little for spring back. 0.271 before seating would give almost zero neck tension, depending on the neck thickness.

I've ran into this myself a few times... but I never had it bell the mouth. It's annoying AF. Made the necks undersized, yes. But there's no connection between that, and the mouth magically belling back out.

I quoted and responded to Diggler because I was answering his question in post #15 , not the OP

The OP has a belled and crushed mouth, looks like multiple issues going on from over sizing/bad die set up/over tumbling

This is what the problem Diggler asked about looks like…

Fired 223