Also, "shadowrunner" is a pretty catch-all term. Look more specifically at your group's power level. They might be less "Ocean's Eleven" and more "Snatch".
The game can be lethal, but there are some mitigating factors. You roll two Attributes for passive dodging, and have several options for more active defense. Also, penalties to ranged attacks are more common than penalties to dodging them. If you do get hit, you roll to resist the damage. Armor helps with this, but more importantly, decent armor can turn physical damage into stun damage, which is a lot easier to recover from. If you do get hit, mundane first aid with a first aid kit adding dice, followed by magical healing, can get you back on your feet again. And finally, using Edge can get you out of some scrapes.
Dice pools in Shadowrun can get high, but keep in mind that dice penalties are supposed to be a major factor. Sure, 18 dice for pistols is a lot, but that's only for optimal conditions - such as facing off with a ganger at high noon and point blank range. When a character is mildly wounded, mildly fatigued, at medium range, firing at a target behind partial cover with rain providing a negative visibility modifier - then that character will be rolling a lot less than 18 dice. Negative modifiers can keep combat from being something where the entire party dies in the first round.
