How to orient a part the same as another part?

So I'm creating a gun, and I'm trying to orient the bullet to be the same orientation as the gun itself, does that make sense. I've tried frames and for some reason, even set to the same orientation, it does not work.

You can using the AlignOrientation constraint. Add an AlignOrientation constraint and an Attachment0 onto your bullet, and add an Attachment1 to a part of your gun.