For those of you just joining us, one of SR4/SR20A's small-but-still-irksome issues is that, of the three skills in the Firearms group, Automatics is far and away the most useful. Pistols covers single-action and double-action handguns, Longarms covers shotguns and bolt-action and semiautomatic rifles, and Automatics covers everything else. Machine pistols (do everything a light pistol does, plus have the option of autofire), submachine guns (do everything a heavy pistol does, plus have the option of autofire), and assault rifles (just plain better in most situations) all fall under Automatics.
I wracked my brain for the longest time, trying to come up with a better way to divide the various categories of firearm, and came up empty. Then I hit on the idea of defining the skills by what you're doing, rather than what you're using.
New Rules
The Firearms group still contains three skills: Short-Barrel Marksmanship, Long-Barrel Marksmanship, and Autofire. Short-Barrel Marksmanship covers pistols, machine pistols, and submachine guns fired in SS or SA modes. Long-Barrel Marksmanship covers carbines, rifles, and shotguns fired in SS or SA modes. Autofire covers all non-Heavy Weapons fired in BF or FA modes. That is, if you squeeze off one round from your Ares Alpha, you roll Agility + Long-Barrel Marksmanship. If you squeeze off three or more rounds at once, you roll Agility + Autofire.
Dumpshockers, am I completely out in left field, here? I can live with the rules not being realistic; Shadowrun has never been particularly concerned with realism, after all. I want this to be easy to learn, remember, and apply, and to make Automatics not be the One Firearms Skill To Rule Them All.