Board Thread:Questions and Answers/@comment-207.155.97.204-20131123081051/@comment-4058379-20131123125953

Most of weapon types available only for certain classes.

Unlocking gun with SC, unlock it for all your characters that can use it, but not for other classes, that can't use it.

If weapon available for all classes (like Pistol or SMG), no matter with what you unlock it, SC or certs, it will be available for all classes, after purchase.