Or simply change work of AC.
When a target is in range of 5 hexes or closer, it's AC will substract current attacker's % to hit, if he uses two-handed weapon, because it's really hard to shoot at mobile target at close room from a rifle, but you can do it with pistol or SMG.
So, if you holding two-handed firearm, and your target within 1-5 hexes from you, you have (current CtH%)-(target's AC)% CtH. If you holding any one-handed firearm, you ignore this.
So now SG bursters will have some advantage of BG, and HtH characters now will be more happy if they reach thier target.
It's obvious. AC = means you're mobile. Maxed AC means you're from Matrix, it doesn't affect you much at long distance, but at close combat you become really fast target for attacker.