I've been playing a shhoting army (Dark Angels) for a few months now and wanted to compile some of the information I've learned about playing with large numbers of long ranged weapons.
Build your squads properly. For Marines, this means no devestators. Use Tacticals. Use even numbers, as theyre harder to score on. Use tactical squads over devestators, with a heavy weapon in each. I like to use a six man squad with a veteran segeant, a flamer, a heavy bolter, and 3 normal marines. These seem to be effective, epseacially since oinly one of my six normal opponents (Chaos) ever gets an armour save against the HB. This set up is also nice for Cities of Death. Taken many of these little squads. They maximize the number of heavy weapons, and they allow you to take off normal marines with bolters for casualties. If an enemy gets too close for comfort, move forward and rapid fire/flame away. If theres anything left, brace for close combat.
Second, deployment is key. Place your men in ranks like this
s s s s s s
M M M M M M
M M M M M M
M M M M M M
What I've done is placed a unit of scouts in my front rank, since they're cheaper, to as as a "meat sheild". If you get rushed my an elite close combat unit (like infiltrating and scouting genestealers) turn one, they soak up your casualties. If you can afford the space, leave 7 inches between ranks, and space them just close enough to maintain consistancy. That way if the units in the front rank get masacred then your entire game isnt over. You move in, rapid fire, and the genestealers or whatever die. Place the weapons with the longest range in the rear for obvious reasons. Remember youre working against the clock and you want to maximize your shots since you'll probably be out-done in close combat if you focus on shooting. So fire away! shoot relentlessly until they reach you.
My third piece of advice is to keep some good close combat units nearby with power weapons ect. They'll help you out if you get rushed and have to engage in close combat. I like to use an HQ and comand squad for this role. Keep them near the rest of your army and counter attack your enemy when the moment is right.
Nowthats what I've found works for me. what works for you? lets start some discussion and hopefully we'll be able to improve each others gaming abilities!