RE: Tumbler
one thing to add about using different head stamp brass, if you have a copy of the Nosler 5th edition, reloading guide (pg46) it shows a great cutaway picture of several different headstamps and the differences in case wall thickness, web thickness and flash hole shape. All variations can affect velocity, pressure and consistency. Hope this helps! Note Ive found Winchester and Federal brass to be the best for me, just my opinion.