Now that I have your attention, I want to compare grav guns to plasma guns. It’s my belief that plasma guns are still superior to the latest out of the imperial armory, the grav gun. I know they are becoming popular weapons among space marine players now, and can be quite good about taking down tough monstrous creatures. If stop to think about it though, the grav gun is only good in certain situations; where as the plasma gun still maintains functionality against anything.
Lets look at the range as the first stat. Plasma guns are 24 inches, all the time. Grav guns are salvo, so 9 moving or 18 standing still. Already the plasma gun has the edge. If you look a number of shots, it starts to balance out. 3/2 for the grav gun means if its in range it will always tie or exceed the shots coming from the plasma.
Okay, so call it a push for the range and shots stats. Lets look at their ability to wound. Against a marine (the standard) plasma wounds on 2’s and grav guns on 3’s. Now say you want to shoot something tougher, say a biker. Still 2’s and 3’s respectively. Terminators make it 2’s and 2’s. When it comes to taking down tough or elite infantry, plasma seems to be the better option.
In fact, if you sit down and think about it, the only cases of the grav gun wounding easier than the plasma is against the following: Riptides, Wraithknights, Wraithlords. I am sure I am missing a few other cases (mephiston I suppose), but those are the big three. Yes, they are common units that get fielded, but they are not the only thing you will see arrayed against you. When you look at the two guns across all monstrous creatures, the plasma gun has the edge.
Now lets look at vehicles. This is where it get a little weird. AV 10, 11, and 12 all are more vulnerable to plasma. AV 13 is a tie. AV 14 is more vulnerable to grav guns. The only things I can think of with 14 all around (outside of forgeworld) is a landraider. So, all vehicles except land raiders are more vulnerable to plasma than grav guns.
So, here is my point. Unless you will be fighting against nothing but land raiders, wraithknights, and riptides, bring plasma guns over grav guns. Yes, there is a risk in overheating, but a marine has about a 5% chance of killing himself with each plasma shot.