Those of you who read my earlier article on the assault phase may be wondering how I view the shooting phase. Clearly, no army will succeed without attempting to claim the maximum benefit from each phase; therefore, I am introducing my combat doctrine as it associates with the shooting phase.
To me, the shooting phase has a lot to do with supplemental attacks, a support for the assault phase. In my opinion, there are three main uses of shooting: 1) A way to crack open vehicles (and get at the units inside!), 2) A way to sufficiently weaken assaulty units to a point where you can safely assault them, 3) Templates, because who doesn't like dropping pie plates all over the place?
1) A way to crack open vehicles, especially transports
I'm fairly sure everybody here understands the concept of melta. I'm a big fan of getting within that cozy zone of 2D6 on the penetration roll; it makes cracking raiders SO much more feasible. In any event, this just makes sense for an army of my operational outlook. Being a primarily assaulty army, we can pack an enormous punch against other armies, given that we can get into the assault with their troops. As a side bonus, when I get close enough to roll 2D6 on the pen roll, it gives me a good chance for my Blood Lance to actually travel far enough to hit its target.
2) Weakening assaulty units
We've all run across them. Units that can absolutely break face in close combat, such as lightning claw or TH/SS termies, TW Cav, Sanguinary Guard, genestealers (due to their high initiative and rending claws), and other units you don't want to throw your dedicated assault units into because of guaranteed high losses or total unit destruction. The answer: dakka. Force any unit to make enough saves, and they will eventually fail one (or hopefully more!). So, volume of fire is important here, but it is important not to get carried away and cut yourself out of an assault phase. With the enemy weakened, you may now go about total wreckage quite happily.
3) Templates, because killing one at a time just isn't cool enough
Orks, nids, and whatever happens to be in front of your vindicator suffers from blast templates. Orks and nids are very vulnerable, for the most part, due to large numbers of troops (ie. even with scatter, your gonna hit SOMETHING), and with their generally poor saves you can kill off large quantities of the ones you hit. Not that space marines can't get hurt from this too; in fact, one of my favorite things to do is flame my opponent's marines after he disembarks from a vehicle.
And that, ladies and gentlemen, concludes my thoughts on shooting in 40k.