Re: Do I need to trim unfired 7mmRemMag brass
It's not important if they're a little longer than the trim to length. That length is a guide to keep you safe from pressure which is caused by excessive case length. If the case gets too long it will extend past the cut chamber and into the rifling and "pinch" the bullet.
That being said, every cartridge has a OAL. Truth is most rifle chambers are longer that this number. Sinclair makes a tool for finding your chambers true OAL.
While it is important to not let you cases get too long, I think it's more important to have them all the same length. Consistency (in every aspect) is the key to accurate reloads. JohnnyK.