Lip around case mouth

[archerforkids]

Anybody had this happen before? Small "flare"/lip around case mouth after resizing. Neck measures .327 except on top of flare. Measures .330 there. .308 Hornady brass. Second reloading. I spun it on some 400 grit paper and it goes away.

 

[TTE]

I don't know nothin .... back your die out a couple of turns and see if it goes away. If it does readjust your die. My $0.73 worth (used to be 0.02 ... e.g. inflation)

 

[1911nut]

Is it a new die?

Did you measure the length of the fired case?

 

[archerforkids]

Strange occurrence. Same die I have used for years for my hunting rifle. Out of 50 cases I had to trim 8 back a little. I'll be scoping the inside of that die before it gets used again.
Thanks for the feedback guys

 

[FTR_Mojo]

Are you sure if was there only after sizing? Looks like the flare you get from leaving them too long in a tumbler with SS media.

 

[Rick300]

I have had that happen. It was from a dull chamfer tool.

 

[WSnyder]

Anybody had this happen before? Small "flare"/lip around case mouth after resizing.

Yes, very common. I bet if you did a general web search you'd find all sorts of people asking this very question. I'm sure I've seen the same question before on this forum. I've had it on my own brass. I suspect it's hardness thing where the case mouth springs back. I never worried about it and just went on with my day. I'd bet if you annealed a case neck and re-sized it wouldn't do it.

 

[JMayo]

Tumbling with steel pins causes it. I don't know what caused yours.

 

[SeabeeKen]

The only time I see that is when the mouth extends above the sizing portion of the die. As the neck is squeezed the brass flows to the place of least resistance and forms a slight bell. this usually goes away after it passes over an expander ball or mandrel. YMMV

 

[KMart]

This was discussed here a long time ago using Redding bushing dies. Reddings answer was that if you are sizing down the neck diameter by more than .005 ( I think) in one stroke, it will give you the belled neck. Sizing down about .004 the first time then sizing down a second time to .006 or more, you won't get the belling. I believe the poster was Cat Shooter.

 

[Bill K]

Strange occurrence. Same die I have used for years for my hunting rifle. Out of 50 cases I had to trim 8 back a little. I'll be scoping the inside of that die before it gets used again.
Thanks for the feedback guys

Think you answered your own question. Those few were slightly over length and your trimmed them back into spec measurements.

 

[Coyotefurharvester]

I doubt the sizing die changed. Your brass definitely changes due to firing/reloading. Part of the whole process is making adjustments.

 

[chop house]

This was discussed here a long time ago using Redding bushing dies. Reddings answer was that if you are sizing down the neck diameter by more than .005 ( I think) in one stroke, it will give you the belled neck. Sizing down about .004 the first time then sizing down a second time to .006 or more, you won't get the belling. I believe the poster was Cat Shooter.

Agree. That and annealing. I first ran into it making 20 practical brass I think.

 

[archerforkids]

Well....as always you folks got me thinking. I will give this proper attention on next batch.
Thanks a million

 

[Lillico]

I do get a ridge at the neck, but it is from the trimming process.
As the cutter removes brass from the face of the neck, it also displaces brass rearward.
I use Lapua brass and wondered if anyone else found this with these cases.
I remove the flared brass with a small belt sander and 1000 grit belts.
This flaring cannot be seen with the naked eye, only by touch or Vernier.
Chamfer tools do not seem effective on this, I've tried a number of them.
I don't want to turn necks every time I reload.

 

[Rick300]

RCBS makes a carbide chamfer tool that works on the lip.

https://www.amazon.com/RCBS-Trim-Mate-Carbide-Chamfer/dp/B0063IDGBS

 

[ditter]

I get this with my Lapua brass. I'm on my 11th firing. I dont tumble with stainless. I anneal every firing. I have a Redding bushing die.

If I size the brass, it drops perfectly into a case checker. If I run an expander mandrel or seat a bullet, I get that flare and the case doesnt chamber. I turned the necks to fix it and it typically stays fixed. Maybe it occasionally comes back on a random case or two. I dont think in my case it is the sizing die, as I used the same die for once fired brass and it doesnt flare. I spoke to a well respected bench rest shooter who said this is just brass "evolving."

I would not recommend power deburring or chamfering. You will thin out the neck at the top and it creates a knife edge. Turn the neck or toss the brass.

 

[Dolomite]

It could be the case is being pushed too far up in the die, back the die off a smidge or trim the brass shorter. This happened to me when using a mandrel die and I ran it up to far which cause case mouth to hit the top of the mandrel.

what is the OAL on the brass?

 

[Rick300]

I would not recommend power deburring or chamfering. You will thin out the neck at the top and it creates a knife edge.

Why do you say that? As long as you don't use excessive pressure or time, they come out perfect. It takes maybe a second or 2 with light pressure and it's done. I would give up shooting if I had to do thousands of cases a year by hand. The cutters that come on the machines from the factory are junk. Replace them with carbide and the rolled lip goes away.

 

[Mark W]

The only time this happened to me, I was sizing cases from .243 down to .22. The lip was small enough that it disappeared when I seated a bullet. After firing and resizing again, everything was normal with no lip.