What is happening here?

[SSL]

Cleaning and prepping a 50 case batch of brass when I found what appears to be cracks at the shoulder/neck junction on two pieces. A fingernail run across them feels like cracks too. The rest of the batch show no sign of this and look quite normal.
This is Nosler .243 Remington brass that has been loaded 3 times (43.0 grains of H4350 and Nosler 80-grain bullets), neck sized (Lee Collet) for each load. Brass has not been reamed or neck-turned. Rifle is a Savage VLP with maybe 200 rounds through it.
I have loaded for over 50 years and have never seen this. Neck splits, case head separations and such, but never a neck separation! Any ideas?

 

[mongo chicago]

If those are the only two out of the bunch, It should eliminate the rifle. I would contact Norma and send them the pics and see what they say. May be a bad batch.

 

[rwj]

Are those defects/cracks located at the end of the neck collet’s downward stroke?

 

[SSL]

Are those defects/cracks located at the end of the neck collet’s downward stroke?

No. Collet ends a bit above the juncture. Very puzzling. Maybe as Mongo said, just bad brass.

 

[243winxb]

Looks more like a cut then a crack? To much pressure applied? http://leeprecision.net/support/ind...e/View/116/0/collet-dies-on-rockchucker-press



Or the brass is to clean , like here? See photos.
https://www.shootersforum.com/handloading-equipment/161050-lee-collet-die-notes-dark-side.html

I have had necks crack and come off, but not a clean uniform cut like yours.

Hope this helps.

 

[Dusty Stevens]

Those look neck turned. Maybe your chamber is tight and they should be

 

[SSL]

Those look neck turned. Maybe your chamber is tight and they should be

Necks are as they left the box. Never been turned. I did polish them up to make the cracks more visible in the picture.

 

[SSL]

243winxb...You have me thinking about if the collet is closing before the end of the stroke causing the neck to be slightly pushed back into the shoulder join as the stroke is completed. This could weaken that area and cause a failure. Worth playing with adjustments. I use collet dies for my .17 Remington and .22-250 but never had this. May be just this die. Thanks for the idea.

 

[JohnKielly]

Maybe this helps. I've posted it before:

Using The Lee Collet Die.
I started using Lee collet dies when they first came on the market and have found that they are very good for the purposes for which they were designed .
I have found that there is a lack of understanding of how to use the die properly and as a result people fail to see the advantages that the die can deliver over standard neck sizing dies.
This is not the fault of the product , it is just a lack of understanding of how the die works and what it will feel like when you operate the press correctly.
Standard dies use a neck expanding ball on the decapping rod and size by extruding the neck through a hole and then drag the expander ball back through the inside neck.
The collet die achieves neck sizing by using a split collet to squeeze the outside of the case neck onto a central mandrel which has the decapping pin in it’s base .
One advantage is that there is no stretching or drawing action on the brass.
The inside neck diameter is controlled by the diameter of the mandrel and to some extent by the amount of adjustment of the die and the pressure applied to the press .
This results in less misalignment than can occur in standard dies because of any uneven neck wall thickness in the cases .
Cases will last longer in the neck area and require less trimming. If cases have very uneven neck wall thickness then this can cause problems for the collet die they definitely work smoother and more accurately with neck turned cases but it is not essential.
When you first receive the die unscrew the top cap and pull it apart check that everything is there also that the splits in the collet have nothing stuck in them then inspect the tapered surface on the top end of the collet and the internal taper of the insert to make sure there are no metal burs that might cause it to jamb.
Next get some good quality high pressure grease and put a smear onto the tapered surface of the collet .
Put it back together and screw it into the press just a few threads for now . The best type of press for this die is a press of moderate compound leverage that travels over centre .
Over centre means that when the ram reaches its full travel up it will stop and come back down a tiny amount even though the movement on the handle is continued through to the stop .
eg. is an RCBS Rockchucker.
This arrangement gives the best feel for a collet die sizing operation.
Place the shell holder in the ram and bring the ram up to full height then screw the die down until the collet skirt just touches on the shell holder , then lower the ram .
Take a case to be sized that has a clean neck inside and out and the mouth chamfered and place it in the shell holder.
Raise the ram gently feeling for resistance if none , lower the ram.
Screw the die down a bit at a time .
If you get lock up ( ram stops before going over centre) before the correct position is found then back it off and make sure the collet is loose and not jammed up in the die before continuing then raise the ram feeling for any resistance , keep repeating this until you feel the press handle resist against the case neck just at the top of the stroke as the press goes over centre and the handle kinder locks in place .
This takes much less force than a standard die and most people don’t believe any sizing has taken place .
Take the case out and try a projectile of the correct caliber to see how much sizing has taken place.
If it’s still too loose adjust the die down one eighth of a turn lock it finger tight only and try again .
Once the die is near the correct sizing position it takes very little movement of the die to achieve changes in neck seating tension .
This is where most people come undone , they move the die up and down too much and it either locks up or doesn’t size at all .
It will still size a case locking it up but you have no control over how much pressure is applied and some people lean on the press handle to the point of damaging the die. A press like the RCBS Rockchucker , that goes over centre each time gives you a definite stopping point for the ram and the pressure that you apply .
There is a small sweet spot for correct collet die adjustment and you must find it , once found , how sweet it is ! Advantages : With a press that travels over centre it is possible to adjust the neck seating tension within a very limited zone. No lubricant is normally required on the case necks during sizing .

If you still cant get enough neck tension to hold the bullet properly for a particular purpose then you will have to polish down the mandrel.
Be careful poilishing the mandrel down and only do it a bit at a time as a few thou can be removed pretty quickly if you overdo it.
You can't get extra neck tension by just applying more force. The amount of adjustment around the sweet spot is very limited and almost not noticable without carrying out tests.
For example , to go from a .001 neck tension to a .002 or .003 neck tension you would be talking about polishing down the mandrel.

There are some other advantages but I will leave you the pleasure of discovering them .
One disadvantage that I have found with the collet die is that it needs good vertical alignment of the case as it enters the die or case damage may result so go slowly.
Also some cases with a very thick internal base can cause problems with the mandrel coming in contact with the internal base before the sizing stroke is finished.
If pressure is continued the mandrel can push up against the top cap and cause damage . If you are getting lock up and cant get the right sizing sweet spot, then check that the mandrel is not too long for the case you can place a washer over the case and onto the shell holder and size down on that.
It will reduce the length of neck sized and give the mandrel more clearance. If it sizes Ok after adding the washer then the mandrel could be hitting the base.
This is not a usually problem once you learn how to use them .
The harder the brass is the more spring back it will have so very hard brass will exhibit less sizing than soft brass because it will spring away from the mandrel more. If this is happening to excess then use new cases or anneal the necks.
Freshly annealed brass can drag on the mandrel a bit in certain cases because it will spring back less and result in a tighter size diameter.
I have experienced it. I always use some dry lube on the inside and outside if I get any draging effect . Normally you dont need lube.
I make up a special batch 1/3 Fine Moly powder. 1/3 Pure graphite. 1/3 Aluminiumised lock graphite. Rub your fingers around the neck and It sticks very well to the necks by just dipping it in and out and tapping it to clear the inside neck . After a few cases it coats up the mandrel .
Other dry lubricants would work also.
Use the same process for normal neck sizing also.

I noticed a definite improvement in the accuracy of my 22-250Rem. as soon as I started using a Lee collet die instead of my original standard neck die.
Readers are encouraged to utilise the benefits of responsible reloading at all times. Although the author has taken care in the writing of these articles no responsibility can be taken by the author or publisher as a result of the use of this information.
John Valentine. © 21/01/2002.

 

[riflewoman]

From the description of the operating principle above, the die is causing this.

The die is resizing by squeezing the neck down in a clamping action. For all practical purposes this is in effect bending the brass. At the neck shoulder junction this is creating a high tensile stress causing a micro crack. A half dozen cycles later and you have an annular crack.

Regular dies apply a compression as the case enters the neck. This keeps the tensile stresses low while the brass is squeezed back into size.

How you work metal matters in the final results. Engineers often specify metallic grain orientation and final work direction of the part.

 

[JohnKielly]

The die is resizing by squeezing the neck down in a clamping action. For all practical purposes this is in effect bending the brass. At the neck shoulder junction this is creating a high tensile stress causing a micro crack. A half dozen cycles later and you have an annular crack.

I suspect that you're correct in this instance, ie that the user is overcycling the die rather than adjusting it to achieve j-u-s-t the necessary effect.

I've use the Lee collet for near 20 years now and have never has this issue with my dies adjusted in the above manner.

 

[Texas10]

I'd section one case to make sure, but I suspect you're applying too much force to the brass and getting brass flow with a sharp fall in pressure at the neck/shoulder junction. Back the die off slightly and see if the issue continues.

When setting up my Lee Collet die for 22-250, I got a similar issue, however I was never able to get run out down to a reasonable level so I switched to a Forster FL die.

I also got a lot of donut formation in my Lapua brass, no matter what die I used.

Are you experiencing donuts?

 

[lrgoodger]

I suspect that you're correct in this instance, ie that the user is overcycling the die rather than adjusting it to achieve j-u-s-t the necessary effect.

Agree. Die is squeezing too far down on the neck. I've found that even getting within .030" of the neck shoulder junction with the collet will mis-align the neck and increase runout. I use a shim washer of the right thickness dropped over the case to limit how far down the collet goes (depending on cartridge and if it needs it). I size only enough of the neck to make sure that the base of the bullet is at least .030" above the lower part of the sized portion of the neck. I got a custom 30BR LCD and it only sizes half the neck (don't need a washer with this one), which is plenty for that cartridge. Runout is less than .001" on every round.

 

[Dusty Stevens]

This appears to be yet another victim of neck sizing

 

[Fotheringill]

How much pressure is the OP experiencing when the ram over cams?

The die may not be in the right place when screwed down or the "tightness" adjustment on the top knob of the die might be too tight.

There should be very little force required when over camming.

I followed Kielly's reprint exactly and get a lot less run out with the Lee than with Redding Competition die and a few others that I have.

 

[SSL]

I thank everyone for their advice, but it seems to be a false alarm! Using a magnifier (old eyes, you know), it appears that this is only the "break" between sized and unsized areas of the neck, much like a "false shoulder". Running a fingernail from the mouth towards the shoulder it feels like a crack. Going the other direction the feeling is nearly unnoticeable. In comparing to my .17 and .22-250s, the shoulder is also present but a bit less noticeable. Funny I have never noticed this before, but evidently enough residual matter had been left on the necks to be compressed into the ridge and made it more visible.

Thanks again for all the advice and thoughts.

 

[K22]

Polishing the necks with 0000 steel wool before placing in the tumbler will remove burnt on carbon from the neck area and prevent it accumulating. My tumbler / media will not remove it so I polish the neck region before placing in the tumbler.