But its not an automatic, so why would it be covered by the automatics skill? the kit just gives it a longer barrel and stock. its still a semiauto firearm firing a pistol caliber cartidge
The most reasonable answer I can give you is that the size of the weapon makes it an 'automatic'.
You can shoot a machine pistol in semi-auto with the pistols skill or the automatics skill, but in every other case (semi auto assault rifle or SMG), you must use the Automatics skill, not the Longarms skill. Furthermore, there are pistols, shotguns and sniper rifles that are capable of burst fire and some full auto shotguns, and they all use the pistol or longarms skill exclusively, respectively. Furthermore, heavy weapons includes machineguns which are all just sized up assault rifles, assault cannons which amount to super-sniper rifles, as well as missile launchers, grenade launchers and other miscellany oddball weapons that don't fit.
It boils down to this: "Automatics" is a size class of firearm, being larger than a pistol and smaller than a sniper rifle or shotgun. It's the size of firearm that's light and easy to use, quick to aim, and has moderate and controllable recoil. More than that, modern SMGs are exactly as you describe - a longer barreled and stocked weapon firing a pistol cartridge - and they all have 'semi-auto' modes as well.
Primarily the reason your weapon skill
should change is because you've changed how the weapon is designed to be held and fired. No longer are you holding your pistol in a deathgrip with opposing push-pull of your hands and a rigid wrist lock to control recoil. It's an entirely different skill to control a handgun through the firing process than a stocked weapon.
Does it make sense? Hell no. It's a game balance thing... and in my opinion, this bit of game balance isn't necessary.
Primarily, the reason you'd break up the firearms skill into so many groups is to penalize characters who can't afford to be flexible and take them all. Your deckers, mages, riggers and the like will only develop one firearms skill and suffer for their inflexibility. They get pinned down by sniper fire, or end up going to the meet at the downtown nightclub unarmed because they can't bring their shotgun. Something like that anyway. Meanwhile the street samurai has at least two or three of these weapon skills and can switch to the appropriate level of firepower for any challenge.
But even the street samurai doesn't have enough skills to just toss around.
In my opinion, all firearms should boil down to "Pistols" for any and all handguns (machine pistols, hold outs, laser pistols, some SMGs and gyrojets) and "Longarms" for anything with a stock (some other SMGs, assault rifles, snipers, shotguns and machinguns). Weapon technique and training is fundamentally similar in either case, but the most difference is between handling stocked guns and pistols. Grenade launchers, missile launchers and flame throwers can all be exotic weapons. They each have their own unique training to use. If we still want to make firing automatic weapons a special thing, we can make using burst fire and full auto a 'martial art' move for 7 karma, otherwise suffer the -3 'defaulting' penalty and lack of specialization.
But I'm not the one who wrote the game, so it is what it is.
