Ok, I'm gunna be completely honest with you. The needler turret sucks.
So I finally modded a map with turrets on it, and replaced it with needles. I realised after the release of Sindewinder that the needler turret sucks and it needs a better, more powerful projectile. Perhaps a plasma pistol bullet charged? Since turrets are under-used anyways, so swapping the projectile with something more deadly could make the stationary weapon become lethal for online and campaign play.
Have a better idea for a projectile? Leave a comment and tell me what you think. But just on a quick note: No ridiculous suggestions and bare in mind that the turret shoots 3 of one projectile at a time so no requests like "rocket launcher" or "scorpion rocket" since that will just ruin game play. Leave a comment, all comments will be read and taken into mind!
The idea of artillery is that you sacrifice mobility for fire power, something that Bungie never understood in their stationary turret concepts. Why else did they incorporate the function to detach turrets? When you're in a stationary turret, you're pure fodder for powerful long distance weapons that players will use. They're also presented with the option to take cover.
The way I see it is that you're gonna need to put something fast hitting and HARD hitting if you want to increase the frequency of the turret's usage. So in that case scorpion shells or sniper rifle bullets would be the best. You have to realize that once the person is in the turret, anyone on the whole map can see him. He could be tagged by the sniper rifles in the bases, rockets from the cliffs, or from the weapons of heavy vehicles like the rocket warthog or scorpion. And since he is enjoying his time blasting away at people, he will be less prone to bale out once he comes under fire. You have to make the trip to the shade worth it, so it give it some real fire power.
P.S. Don't give any plasma projectiles for the shade, they're too slow and their range is way too limited.