About the rail gun I wil give some advice which works for me.
The railgun has a few characteristics.
The sound of the gun charging is easy to recognize in a loud battle, make sure to pay attention.
The sound also pitches higher if it's about to fire.
The rail gun has a rather small area of affect compared to other power weapons.
Now why am I telling you this?
It is also one of the most easy weapons to dodge, making use of a thruster pack or hardlight shield should prevents the rail gun from doing a lot of harm.
As someone who used the hardlight shield a lot, the actual shot is easy to block due to the high pitch.
The same thing counts for the thrusterpack, however damage is less avoidable.
BUT COOOOLDFREEZE, I can't hear that sound if it is being fired from a long distance!?
I hear you, my little spartan brothers and sisters,
Well the Railgun also offers the pleasure of showing when it is about to charge, due to the blue glow it emits when it is almost ready to fire. At first this might seem difficult to time, but getting to know the high pitch is also getting to know the blue light.
The other being that it still needs some travel time and dodging it with a thruster pack is likely to give no damage at all.
Another thing I do against a rail gun, is closing the distance. First of all to stagger your enemy. second, most people use p34nuts technique, zooming in, this technique could be handy, but most people think it is the same as sniping. ever tried sniping someone from up close while zoomed in?
My tips for using the rail gun:
1. get a feel for the weapon, knowing when you fire and where it is going to hit, is a quicker and faster way then using the zooming in technique.
2. The rail gun is great for throwing vehicles of balance, not considering the banshee and or mantis ( While it drops the mantis shields quite low to be honest.) Ever tired of getting ran over by a rocket hog? Blast a railgun bullet at the side and watch that thing fly.
Also thanks to p34nut for not forgetting that we used to be a team