What am I doing wrong here!!

Did you prep the brass? Chamfer ?
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If you said you loaded many fired cases and had no problem with the same dies then the neck diameter of fire formed
cases get sized with more spring back leaving 1 or 2 thousanth's more open inside diameter. The new cases may have spring back the other way after pulling expander ball thru creating tighter neck on new brass. Fire a few newly loaded and try again... may work out after fire forming a bit.
As Dmagn said... Chamfer inside and outside on new cases.
 
Just shoot the cases in your chamber to fireform if you will. I bet your neck tension will be normal on second loading. Seems Lapua always has very tight necks on first firing. Easy peasy!

Paul
We are on the same page
 
Here are the measurements…

virgin brass
Neck ID .260
Neck OD.2885

virgin brass FL size
Neck ID .261
Neck OD .2895

2x fired brass
Neck ID .265
Neck OD .2945

2X fired brass FL sized
Neck ID .2615
Neck OD .288


I guess the big question for me is what changed? The first hundred brass that I did I had no neck tension issues. Now all of a sudden I'm having neck tension issues. It's like I set up the dies wrong, or the expander ball inside the dies got worn down which doesn't seem possible.
 
First thing I notice is your sized ID is 0.261"+/-, OD os 0.264"nominal so that's not likely the problem. Your virgin brass at 0.260" with no chamfer and dry could very well be an issue. Is the FL sized with or without the expander ball? It's a border line a silly question but are you sure the expander is passing all the way through the neck on the downward stroke?
 
I take fine steelwool to my expander before putting them to use...and clean them..irregularly.....
BUT....
I swab the necks on my brass before resizing...lets the expander slide thru easier...less run out.....
It's all about figuring out your problem....fixing it....staying with a routine.......you may change later...but figure out the little problems before they drive ya nutsso...
 
I took some 1x fired and they loaded like butter.
This very well may be because the dies is not sizing the neck of the virgin brass because the virgin is already less. One gentleman bumped on this but that would support the fired vs virgin. Fired brass typically has a little powder residue still in the necks for a little lube, virgin and SS tumbles are very grippy.
 
Here are the measurements…

virgin brass
Neck ID .260
Neck OD.2885

virgin brass FL size
Neck ID .261
Neck OD .2895

2x fired brass
Neck ID .265
Neck OD .2945

2X fired brass FL sized
Neck ID .2615
Neck OD .288


I guess the big question for me is what changed? The first hundred brass that I did I had no neck tension issues. Now all of a sudden I'm having neck tension issues. It's like I set up the dies wrong, or the expander ball inside the dies got worn down which doesn't seem possible.
Did you anneal yet ?
 
You guys might want to stop helping me. I'm about to have a fire sale on a bunch of components! 😆

Loaded neck OD .291

I chamfered. Just tried annealing too with no change in virgin brass. I take back the comment about it loading easily on 2x. Tried again. Still hard.

heres a picture of the expander on the Rcbs. It's obviously getting some work.
 

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Anybody in Thornton Colorado want to come over? Lol!

I've been meaning to get rid of an extra pack of elk back-straps.
 
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