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Unusual reloading issue with brass, at least for me, help please

DngBat7

Silver $$ Contributor
So I am having an unusual reloading problem that many of you may know the answer for. I had new lapua brass in 6.5cm. Turned the necks about down to about .0132. When i went to reload, Tumbled, annealer, sized in Whidden custom die with .288 bushing. So I went to seat the bullets, I use a hydro arbor and noticed the psi was off the charts. So I checked and almost all the brass I sized the necks were .288 at the very top near the mouth, but in the center of the necks were anywhere from .265 to .270 which explained my extreme seating pressures. This is very strange to me and I have never seen this. Almost like the brass on the necks got “sucked” in from firing, maybe? Has this happened to anybody?

I also noticed it happened to some Hornady brass, so not lapua specific. The only thing I do know is if may be it only happened to my neck turned brass? I had to run all the brass through the expander die and then resize to fix it all. But this will ruin the centricity of my brass, won’t it?
 
I have always found the necks of new lapua brass to be tight. Always use an expander mandrel on new lapua brass.

You used your turning mandrel as an expander when you turned your brass correct?

Best fix is a mandrel that will give you the neck tension you are looking for. Using an expander mandrel should not effect brass concentricity.

Could be you have a bad bushing. Do you have another one you could try.

New brass with no carbon in the necks or not lubricated before seating always has readings way too high with my hydroseater.
 
I have always found the necks of new lapua brass to be tight. Always use an expander mandrel on new lapua brass.

You used your turning mandrel as an expander when you turned your brass correct?

Best fix is a mandrel that will give you the neck tension you are looking for. Using an expander mandrel should not effect brass concentricity.

Could be you have a bad bushing. Do you have another one you could try.

New brass with no carbon in the necks or not lubricated before seating always has readings way too high with my hydroseater.
I meant to say I did use a expander mandrel before turning, and I did check the bushing and it is good. Also, I used Redding media to lube.

On another note, expander mandrel can be used between firings, not just used when turning?
 
Yes, if you want .002 "neck tension" use a .262" mandrel ( .002" under bullet diameter.)

By the way, how are you measuring neck thickness?
 
Try chamfering the inside of the mouth and check seating force again. Could be that you've peened the case mouth and have a "donut" on the inside edge. You'd have to chamfer inside and outside to get back to your thickness reading (if this is the problem), but doing just the inside should relieve any excess seating force.
 
How much did you cut into the shoulder when you turned necks? Sounds like a big donut.
 
So I took a closer look at everything. Tell me if you think this is possible. I think I made a mistake turning new brass and then fire forming. I turned it and shot. Headspace grew by about .003-.004. And if you look close, it looks like some brass from the shoulder was pushed into the neck. Which the thicker brass at the bottom of the neck, may have compressed the center of the neck smaller during firing??? Not a scientist, but thinking now NOT to turn brass first on a chamber that is not undersized until there is a few firings??
 
Almost like the brass on the necks got “sucked” in from firing,

If fired brass? Sizing the neck down more then .008" in one step may reduce the necks OD to less then the bushings marked size..

Larger at mouth- There has been a few posts where the case mouth has a flare after being sized with a bushing. Have not seen a reason why it happens?
I run a fired 308 into a 243 fl bushing die, with no bushing installed. I got the mouth flare.

So, if sizing fired brass down more that .008" , try sizing down in 2 steps.

If new unfired factory brass, no idea.??
 
If fired brass? Sizing the neck down more then .008" in one step may reduce the necks OD to less then the bushings marked size..

Larger at mouth- There has been a few posts where the case mouth has a flare after being sized with a bushing. Have not seen a reason why it happens?
I run a fired 308 into a 243 fl bushing die, with no bushing installed. I got the mouth flare.

So, if sizing fired brass down more that .008" , try sizing down in 2 steps.

If new unfired factory brass, no idea.??
I am sizing down .007 or .008. And I am getting a flared mouth. Sounds like this actually be my issue. I’ll give a try. Thanks
 
Could the die be defective? The hole in the die undersize? Try sizing a fired case with no bushing installed. Measure neck OD before and after sizing.

Just another guess.
 
Could the die be defective? The hole in the die undersize? Try sizing a fired case with no bushing installed. Measure neck OD before and after sizing.

Just another guess.
You were correct. It was from making two big a jump with one bushing. Trying to do .008 in one pass flared the mouth. Good to go
 
Old Thread .


So I checked and almost all the brass I sized the necks were .288 at the very top near the mouth, but in the center of the necks were anywhere from .265 to .270 which explained my extreme seating pressures.

Something else to check.

Could this be the cause? http://forum.accurateshooter.com/threads/case-mouth-doughnut.3983036/page-2
The cases hit each other as they are tumbled, and the soft annealed case mouths get hit and become peened. Meaning thicker and with a sprue like edge on both sides of the case mouth.
After a few loading, could be possible??

See photo.
 
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