Thread: 300BLK cas thickness problems

Hi there
Ive bought some pre formed brass made from mixed .223 ...
I have found most chamber good as gold once primed/powder/pill but.... but some once the pill is seated will no longer chamber correctly and force is needed to eject round ....ive chambered the empty case,it chambers and ejects fine ...load a pill into it and it will no longer chamber properly nor eject
From what ive been reading it may come down to diff thickness in the brass ....
Im trying to find a way to make the neck smaller ... is there a die that I can use to alter the neck ? ... Ive been reading about Reaming .. but im kinda going around in circles trying to look into that one ...
If anyone has any ideas including where to source from please let me know

Sean