yes, that way you can convert some of that brass you have been saving. Just use your most undesirable case mouth cases because they are going to be cut off anyway.
A lot of blk shooters get free brass because it is too thrashed to reload 556, like stepped on at the range or nicked case mouths
for trimming after fire just use a standard trim lathe.....or a device like the Little Crow Gun Works WFT, my new favorite.
for the factory rounds you buy, just measure the case after you do the deprime/size stroke on the press.
1.fire
2.clean brass
3.inspect for cracks
4.lube case, a couple techniques there
5.set up die per instructions in die box
7.insert brass and run up into die, primer falls out and the case is squeezed to shape, shoulder reshaped
8.depending on press you reprime on the next stroke and the expander ball expands the neck to receive another projo
as you fire the brass case expands and "flows" aft and fro filling the chamber.
as you do step 7 and 8 the die takes the brass that flowed up the chamber, shoulder and neck , and pushes it back into shape. This process leaves the brass in a stretched state, this is when you want to measure and trim to spec because no other time in the life of the case it will happen again till its fired.
If you trim to the low end of the spec it will be quite some time before you trim again. The blk will be easy on brass so it wont harden and crack as fast.
