Editing Warhammer 40,000/7th Edition Tactics/Space Marines (section)

====Heavy Weapons====
*'''Grav-Cannon'''
**A bigger grav-gun with Salvo 3/5 and 24" range.  These come with a Grav-Amp by default, which gives re-rolls on To Wound or Armor Pen against a vehicle. As a Salvo weapon, they're the only heavy weapon a Devastator squad can fire at full BS after moving or disembarking from a transport (albeit with half range and the lower number of shots). Extra rage-inducing on Devastators taken with the Skyhammer Annihilation formation, due to Devastators being able to Relentlessly disembark Drop Pods and fire full range/shots. They're also ''comically'' undercosted at 35 points a pop for Tacs and Devs, and 25 pts each for Centurions. Bad against light infantry (Guard blobs, Dark Eldar, Orks), and weak against Superheavies due to their immunity to Immobilize results, and by extension Hull-point stripping from Immobilize spam.
***Seriously though, Grav-Cannons+Gravamps are CRIMINALLY underpriced. According to [[User:Evilexecutive#Fast_Approximate_Intrinsic_Value|FAXIV]], which admittedly does not handle the nature of Grav weapons well, the value of a 5-shot AP2 gun that has a 97% chance to wound per hit (89% vs 3+, 75% vs 4+) is a ''monstrously huge'' '''75 points''' per gun. On average, 3 Grav-Cannons with Grav-Amps at BS4 at full firing rate (i.e. 3 Dev Centurions) will kill 6.48 Terminators or Immobilize any non-Superheavy vehicle three times (resulting in the removal of 5 HP) per turn of shooting. Cackle manically as you wipe a riptide out in one turn of shooting.
****FAXIV is a gross oversimplification, of course, but you get the general idea.  One of the harder to analyze attributes of these things is that better armour saves normally raise the cost of a model, so Grav weapons have a tendency to have a net effect of your opponent paying more points to reduce their models' survivability - used intelligently, you will quickly recoup their cost.
***This is the best weapon to equip minimal-sized Tactical Squads with. The squad provides some anti-infantry firepower in the form of Boltguns (and maybe a combi-flamer on the Sergeant), while the gun enjoys being surrounded by expendable mooks and covers anti-heavy infantry, anti-MC and anti-tank roles splendidly.
*'''Heavy Bolter'''
**At 3 shots, S5, and AP4, it's a heavier, meaner boltgun. Good against hordes since it chucks out reasonable dakka, and not horrible against AV10 (Sentinels, Land Speeders, War Walkers, rear armor, etc.), but any of the other options below are preferred. However, Imperial Fists get more out of Heavy Bolters thanks to their Chapter Tactics (re-roll 1s for Bolter Drill, and Tank Hunters thanks to Siege Masters.)
*'''Heavy Flamer'''
**An Assault 1 S5 AP4 template (but listed in the Heavy Weapons list, for some reason). Much more effective at horde-crunching than the Heavy Bolter, but much shorter range. Overwatch "Wall of Death" with this can be VERY painful. Though it's listed as a "heavy weapon" wargear option, its rules are Assault 1 (''not'' Heavy) so you can move, flame, and charge. However, only Terminators, Sternguard, or Legion of the Damned can grab heavy flamers, so low distribution hurts an otherwise great weapon.
*'''Lascannon'''
**An S9 AP2 weapon, good against vehicles up to AV 13 and TEQ. It's an anti-tank and anti-MC weapon, so you still have to bring something else for horde control. Usually seen on backfield Devastators and Predators, since its range is very good you can stay back and pop vehicles all day long.
*'''Missile Launcher'''
**With two different payloads - S4 AP6 Small Blast for massed light infantry, and S8 AP3 for vehicles/MCs - this thing trades effectiveness on specific targets for versatility. However, in larger armies, it's better to take several squads each equipped with more specialized weapons instead. Note, however, in very specific circumstances, Krak Missiles give it a perfect mix of low cost, decent range, and just enough S and AP to deal Instant Death to multi-wound T4 models with 3+ or worse, and is thus the cheapest weapon to splatter a Tyranid Warrior/Nob (or MEQ HQ) from half the table while letting you later put out Frag Missiles for their weenie hordes. Can also pack Flakk Missiles to deal with Flyers, but again, unless it's a low points army that needs versatility in every unit, you should never do this - not when you could take the specialized anti-air ability of the now-excellent Stalker tank (besides, "anti-air" weapons can shoot at Skimmers at full BS, which makes some of them workable against Eldar/DEldar/Necron armies). Overall: good in low points games due versatility, bad in high points games where you should take specialized weapons instead.
*'''Multi-Melta'''
**A Meltagun with twice the range, which means that its 2D6 Melta-effect range is now 12". Same S and AP, though. Good in Skyhammer Annihilation Devastators since they are relentless for a turn. 
*'''Plasma Cannon'''
**An S7 AP2 blast, good for taking out freshly deep-struck units (like enemy Terminators) that are still tightly clustered, or just wreaking havoc on all kinds of infantry. Like its little brothers, the Plasma Gun and Plasma Pistol, it also has Gets Hot! Unfortunately it is a very mediocre choice, because Small Blast kinda sucks (begging the question of why it's so different from its siblings - presumably it should either be Heavy 3 without blast, or the Gun should be blast and the Cannon should be Large Blast).
***The haemotrope reactor can fix the small blast problem if you need to explode everything.
***If you're running a 10-man tactical squad, the cannon isn't a terrible choice as it adds anti-infantry punch to your shooting (what else is your tactical squad doing?).
***Veteran players will space out units, but that's usually because, at some point, a plasma cannon raped their horse and ate their parents.  These things can be incredibly punishing against unprepared foes (much moreso than other weapons).