Do you have to trim to lenght once fired brass? I got a bunch of Norma .308 once fired, a friend thats being hand loading for years says he doesnt trim once fired brass, so I thought I would ask here.

I particularly trim once fired brass to the length most appropriate to my chamber or to the standard length as circumstances dictate. This does 2 things. First it ensures that the crimp or neck tension is as similar case to case as possible. Second, it squares up the case mouth which also helps make case release of the bullet as consistent as possible. I don't ever rely on what somebody else told me they did. I only depend on what I know I've done, myself. Even new out of the bag unfired brass needs to be trimmed even if all you do is square up the case mouth. I've often found cases from makers of quality brass that has inconsistencies that are unacceptable.

I do this, but I'm not one of those guys that weighs his cases or standardizes all the flashholes. I only do those things if a cursory inspection (usually during the trimming and chamfering process) reveals other problems.

I trim all brass that is new to me , whether actually new or been fired. I dont trim after "my" once fired but I do check for OAL.

I always trim new brass after the fire forming shot. Even if I have to cut it a bit short. As Hobie sez, it does things for you besides making them all the same length.
After that, I trim as needed.

Depends. Some cases "grow" enough each time they're fired to require frequent treimming. The .308 Norma is NOT one of these! But you must ALWAYS trim IF the cases are over max, or if some are longer than others, and you want uniformity in the performance of your ammo. So measure them! Then you'll know if they are too long, or if some are longer than others, thus needing a trim!

Most all new brass is too short for the chamber to start with so I don't know how you would trim it to fit your chamber...I do trim it barely to get them all the same length to start with...then it will stretch to the chamber, when it gets too long then trim it back 10 thou...just keep them all the same and check your loading books for OAL and trim length...

I suspect thats why your friend doesn't bother.....

First full length resize the brass. Then measure the over all length. If the brass is to long, trim it.

Wouldn't you want to trim them all to the same length just to chamfer the case neck to make seating the bullet as consistant as posible? I would.