I just had a tool-tip explain to me that the Combat Rifle is considered an automatic weapon. Does this mean that it doesn't benefit from the Rifleman perk? I'm predominately using single shot Combat Rifles, have I been investing in the wrong perk?!

Depends on if you put an automatic receiver in it or not.

If you click and it shoots one time, it is not an automatic weapon.

Assault rifle, combat rifle and combat shotgun can be full-auto or semi-auto, depending on the receiver they have. By default, they're all semi-auto (fire once on one trigger pull).

Well, phew. But then that load screen tool tip needs to change, because it flat out stated that the Combat Rifle was an automatic weapon.