The Speer Manual says you should trim your cases as the first step (or maybe second; I don't have it with me), which I have been doing. However, many cases are actually shorter after firing than the recommended length, so I was not sizing.

On the neck-sizing question I asked, someone said that this could happen because the explosion could set back the shoulder a bit.

So I figured that I should see if the brass had stretched at all during sizing, and sure enough, I had a few cases that were within a few thousandths of the maximum, so I went back and trimmed all the sized cases.

So: am I doing this right? Should cases be trimmed before sizing, as in the Speer Manual, or should they be trimmed after sizing?

kk

Do trimming after sizing.

Since resizing stretches the case, you should trim after resizing.