Do you trim case before FL resize?

[tteng]

I was FL sizing range-pickup 308 cases for the first-time. After I resize a bunch, I measured/found the OAL were too long for some. So I file down some and remeasusred OK. Question, even after I chamfered the neck inside-rim, I still get copper sliver (build-up between the case/bullet) while seating the bullet. The Lee dies I'm using is brand new. What did I do wrong (did I not chamfer enough)?

[NRAhighpowershooter]

You trim after... and filing???? you should be using a case trimmer not a file... that way the case mouth will be uniform..

[tteng]

Well, I'll be getting a case trimmer soon...
I didn't muscle the case w/ the file..I did it kinda like my wife buffing her nails, so I didn't think I deform the case-rim. Or maybe I did..
BTW, if my 308 case length vary between 2.008 to 2.0145", how much pressure/accuracy difference would it be ( I loaded it pretty light, 41gr BLC2 behind 150gr spitzer, non-crimp) Would tight-neck (or sliver build-up) cause overpressure problem?

[30Cal]

FL Size, then trim (otherwise, they'll all be different lengths when you're done). Trim length is going to have a minimal affect on accuracy, especially with no crimp.

If you are shaving brass or copper, it can end up in the chamber or barrel. I make sure to break off the occasional sliver that might show up after seating.

[ivanimal]

I only use a case trimmer. I have never used a file. I would think it to deform the cases at least a little.