[Sabre9mm]

My new(used) Mossberg 325

The side of this weapon reads not for use with slugs right below the stock choke description, which is *full*

Can I not put a straight tube (Assuming they make such a thing for it) in with zero choke and still fire slugs, or is the warning just final for all slugs regardless of what is the terminating diameter of the barrel?

I assume it would potentially cause damage to shoot with the choke removed...?

Likewise does anyone have a chart resource detailing what can/should or not/and does best as far as round type and choke flavor?

shotguns are a new game to me,so I ask forgiveness for newbie questions, just need a prod in the right direction to start some research.

Thanks