According to the description of the skills, increasing the railgun skills only unlocks the next railgun. And I'm sure if you unlock the proto forge gun, you will see that even the best fitting on a sagaris can't hold up at all. About 4 shots is all it takes with the best shield extender and the best shield booster running at the same time. The only option is to try to hide or run if you can react in time and have an escape route. Trying to stand and fight against a forge gun is suicide, this shouldn't be the case when you consider it's an HAV vs Infantry. It's hard to hit someone direct with a rail gun so you rely on splash damage, proto heavies are at an advantage with even minimal cover. I'll give some of these guys credit though, I had one jump on top of my tank with a forge gun, I had to get out and shoot him to get him to jump off. If I didn't have a gunner at the time, he still would have finished me off. I don't mind being taken out by someone with skill, but camping on top of a tower taking cheap shots at large targets with an OP weapon is a different story. That's why I'm upset that they nerfed the remote explosives, at least when those get you, you know you were bested by someone with balls.

Proto swarms are almost worse since you can't avoid them once they are locked on.

The point is that a Marauder should never be an easy target, regardless of how good your gear is. It should take no less than multiple people attacking it or another marauder, or at least another HAV. Even the standard tanks should be more of a concern to an HAV driver than a Heavy which isn't the case. This makes no sense to me.

And like I said, I don't think the forge gun should be rendered useless, it should still be effective against an HAV, just not that effective. If you think I'm doing it wrong, unlock a marauder and see for yourself what it takes to keep them alive.