I've been gathering data on the amount of armor a round could penetrate. Sometimes my sources agree, sometimes they are close, and sometimes they are far apart. So I decided to include all data in the tables. That is why you may find several penetration factors for a particular weapon.
Also my sources sometimes don't agree on the names of the weapons. Thus I've included them as they are named in the publications. So it may be possible that the exact same weapon is listed under a couple of different names.