1) The alien ships are manuevering, so just firing at the reticle isn't going to always cut it.
2) If you're using full guns, the reticle isn't accurate for all the weapons, since not all the bolts travel at the same speed. (I can't remember if it's the fastest, slowest, or average of the weapons.) So you end up missing with all of them, potentially.
3) Getting up close reduces #2, since the spread is reduced because the shots don't travel for as much time.
4) Quick, short bursts are the best. I find I'm much more effective when I only fire a quick burst when I'm fairly sure I'll hit. If I miss anyway, I take a breath, adjust my aim, wait a fraction of a second, and fire another burst. Just wailing away is usually a recipe for an empty gun capacitor and missed opportunities.
When you have all of your guns available, you can usually decimate your opponent pretty quick with bursts. On the other hand, if your capacitor runs down and you're forced to bang away at their shields with a measly couple lasers firing every few seconds at unpredictable intervals, all you're going to do is let their shields absorb all the punishment.
I find that using the above tactics makes me a bug-killing machine. It's almost scary how quickly you can wipe out a bug squadron with minimal use of the guns. I find the Kilrathi in the previous games to be much harder gunnery targets, although that might be because my joystick doesn't work in DOS...
--edit--
P.S. There's no shame in using the missiles, even if you get most of your kills with guns. One of my favorite techniques is to "ripple fire" my missiles when there are a lot of bugs. Basically, I keep toggling through hostile targets, letting loose a missile at each one, until I use up all the ammo I want to expend on that stage. Besides giving you the feeling of kicking the insectoid ass of the invaders, it actually does help soften up or destroy the swarms before you close for the knife work. FFs are handy for batting away the occasional tailer who tries to interrupt your gun play. Prophecy and Secret Ops give you such an abundance of missiles, it'd be a shame not to use them.
--edit2--
Oh, and when you really get in the zone, you can take advantage of the fact that different guns have different speeds to sorta smear your shot out across their hull. Once you've been shooting away long enough, you sorta get a sense for the speed and can kinda feel when you can really nail the buggers.
--edit3--
Just to reiterate something someone else said, you should consider switching targets if it's too hard to line up a shot. Often, following a single target blindly means you spend more time trying to line up a shot than delivering ordinance. Switching rapidly (to the nearest target is usually convenient) means you can keep the bugs off balance, by attacking one, then the other. Of course, you shouldn't do this so much that the other guy has a chance to recharge his shields.
2) If you're using full guns, the reticle isn't accurate for all the weapons, since not all the bolts travel at the same speed. (I can't remember if it's the fastest, slowest, or average of the weapons.) So you end up missing with all of them, potentially.
3) Getting up close reduces #2, since the spread is reduced because the shots don't travel for as much time.
4) Quick, short bursts are the best. I find I'm much more effective when I only fire a quick burst when I'm fairly sure I'll hit. If I miss anyway, I take a breath, adjust my aim, wait a fraction of a second, and fire another burst. Just wailing away is usually a recipe for an empty gun capacitor and missed opportunities.
When you have all of your guns available, you can usually decimate your opponent pretty quick with bursts. On the other hand, if your capacitor runs down and you're forced to bang away at their shields with a measly couple lasers firing every few seconds at unpredictable intervals, all you're going to do is let their shields absorb all the punishment.
I find that using the above tactics makes me a bug-killing machine. It's almost scary how quickly you can wipe out a bug squadron with minimal use of the guns. I find the Kilrathi in the previous games to be much harder gunnery targets, although that might be because my joystick doesn't work in DOS...
--edit--
P.S. There's no shame in using the missiles, even if you get most of your kills with guns. One of my favorite techniques is to "ripple fire" my missiles when there are a lot of bugs. Basically, I keep toggling through hostile targets, letting loose a missile at each one, until I use up all the ammo I want to expend on that stage. Besides giving you the feeling of kicking the insectoid ass of the invaders, it actually does help soften up or destroy the swarms before you close for the knife work. FFs are handy for batting away the occasional tailer who tries to interrupt your gun play. Prophecy and Secret Ops give you such an abundance of missiles, it'd be a shame not to use them.
--edit2--
Oh, and when you really get in the zone, you can take advantage of the fact that different guns have different speeds to sorta smear your shot out across their hull. Once you've been shooting away long enough, you sorta get a sense for the speed and can kinda feel when you can really nail the buggers.
--edit3--
Just to reiterate something someone else said, you should consider switching targets if it's too hard to line up a shot. Often, following a single target blindly means you spend more time trying to line up a shot than delivering ordinance. Switching rapidly (to the nearest target is usually convenient) means you can keep the bugs off balance, by attacking one, then the other. Of course, you shouldn't do this so much that the other guy has a chance to recharge his shields.
