Strictly my personal taste, but I think that there are WAY too many gun combat skills. Is pointing and shooting a laser pistol vs a Colt 1911 at a target less than 10 meters away (typical pistol combat range) really so different that it requires a unique skill?
Indeed not. Having grown up with my trusty laser pistol, however, the first time I pick up a briskly loaded 10mm I may not shoot it as well.
On the other hand, if I have been leading moving targets all my life with a shotgun, the first time a pick up a laser rifle and try to lead....
Ballistic v. speed of light. Single shot v. auto fire. The paintbrush of a shotgun shooting at a small, moving target v. the mechanical pencil of shooting a rifle at a very stationary target. Too many loose ends based on my understanding of ballistics (and lack thereof). I would join Simon's comments about most slug weapons being fairly close, but I doubt how many lasers and PGMP's were thrown into his experience. One thing I have noticed is that great rifle shots often make bad wing shooters; having grown up with a healthy mix of bolt, semi- and full-auto, slugs and pellets, it was easy for me to take this background for granted beginners.
That said, any pistol at pistol range has more to do with any other pistol than a Gauss rifle on auto fire does with a bolt gun at rifle range.
That's why I think having mutually exclusive (CT), or overly inclusive (MgT) weapon skills is a mistake.
I have slug rifle, I can shoot any slug gun with no penalty; but I can't fire anything on full auto or burst (rifle or no) at my skill level, nor get an autofire bonus without autofire (call this SMG, and I wouldn't argue semantics). I can fire a shotgun with slugs as a rifle; a shotgun fired as a shotgun (w/ pellets shot at small, flying targets) I can shoot with no penalty, but not use slug rifle skill. (No slug; no rifle.....
). Energy Rifle includes all sorts of plasma/fusion stuff that Sgt. York might get himself in real trouble with; so Slug Rifle gets any laser without penalty, but no F's or G's. Combat Rifleman gets the benefits of both slug rifle and SMG. Slug Rifle gets grenade launchers, but can get into trouble at short ranges. Not as logically neat, but closer to the truth along functional lines while avoiding overspecialization.