Ridge at brass mouth after sizing

[DIYguy]

Getting puzzled here with a development with my 308 brass. I'm discovering a slight ridge around the outside edge of the mouth of my brass after sizing. It's not much but I can take my thumbnail and catch the ridge rather than a smooth neck. This ridge when discovered can make a bid difference in my bullet seating. I can feel the difference when seating a bullet when the ridge is present as it increases the neck tension, in some cases a LOT. Running the neck through the case prep and chamfering the inside and outside of the opening helps but sometimes it takes quite a bit to get rid of the ridge. Best method I've used is small piece of fine emery cloth and spin the brass with my fingers to polish the ridge off.

Lapua brass, annealed after every firing, tumble cleaned, sized in Forster CoAx press with Redding Competition S die and neck bushing. Probably about 4th firing and already been trimmed once, brass length is 2.012.
Ridge is PIA as can make the difference of round gong into battery and messing with neck tension and my chrono specs. LOT of work to get rid of it.
Wondering why I'm getting a ridge?

 

[spife7980]

How is a ridge around the outside effecting the bullet seating on the inside? Sounds to me like it got trimmed too fast with too dull of a cutter so its swaging the bass over and out instead of just cutting it clean and square.

In either case, a good healthy chamfer and deburr on every firing. If your case prep center has trouble with it you probably need a new sharp blade, brass is soft and cuts easy.


And its only there after sizing, not before?

 

[lash]

Like @spife7980 says, you should ID and OD chamfer every time you load, before you size. That’s for starters. By doing that, I rarely have to trim to length. You don’t have to Chamfer the crap out of them either. A light inside/outside chamfer each time to every piece of brass leads to more consistency, imo.

Having said that, Spife’s last question could lead to your issue, maybe, depending upon what your answer is. I seem to recall someone on here a while back having a similar issue and it was being caused by how deep the center depriming mandrel of the die was inside the die body. It was contacting the top of the neck, causing the damage.

That’s not to say for sure it’s your issue, but it’s a possibility.

Oh, and as mentioned, your chamfer tools should cut the brass like butter. If they don’t then you need new sharp ones that will.

 

[DIYguy]

Brass has already been fired and preped since it was sized using the Hornady Trimmer.
Don't notice a ridge after its fired, just after sizing.
When the bullet is seated the die is working of the outside of the case neck. The extra ridge is causing the neck to compress more as compared to a stardard straight neck. Practically no effort to seat a normal round, can really feel the extra force if there's a ridge. Can even see flecks of copper for cases with a ridge.
Now I have to go through every case and do the thumbnail test and do a full chamfer prep and emery to get rid of the ridge.
Still puzzled what's causing it. Loaded about (800) rounds of 308 for the match gun and at least equal for the 6.5. This seems new.

 

[lash]

If you didn’t see it already, please read my response right above your reply. ^^^^

 

[DIYguy]

....Post crossed when typing and hitting enter.
My Hornady prep center died (don't recommend) replaced with Frankford Arsenal Platinum last week.
Interesting thought on the mandrel but I have the pin less than 3/16 beyond the die, I'll have to dig into that one deeper.
Normally to chamfer it only takes a light touch but that's not enough to get rid of the ridge, takes a final wipe with the emery cloth to completly get rid of it.

 

[Gatorshark]

case lube you are using?
chamfer before resizing
expander and die clean?
tried backing off mandrel and or die?

Things I would check.

 

[Pvt.Donut]

Are you wet tumbling with stainless steel pins by chance? SS pins gave me a ridge but Chamfer/deburr clears it up. Again, make sure you're Chamfer and Deburring every time.

 

[DIYguy]

Case lube: Dilion
Chamfer after sizing: Wet tumble clean about 40 to 45 minute, dry, anneal, size and decap, wet tumble about 30 minute to remove lube, tumble another 15 minutes with Wash-n-wax. Chamfer and primer pocked clean after wet tumble.
Yup to clean expander.
And now for something different. I just went out to check the sizing die and noticed my decap pin was off center. Took the die apart and my spindle is bent. Not sure how well is shows up in the photo but the top of the threaded body just below the middle portion of the spindle is slightly bent. I've bent a lot of spindles for 9mm before I stopped using pins but this is a firtst.

 

[spife7980]

When the bullet is seated the die is working of the outside of the case neck.

When the bullet is seated the die shouldnt be working the neck at all.

Take the seater apart, does the bullet fall through freely? Does the case insert into the die freely. If so then you only feel it when actually seating the bullet? If so that would lead me to say that it is the internal diameter thats not chamfered and the bullet is snagging on the edge of that.

Got a picture of this hanging edge?