Simple enough. A missile version of the concussion mine. The concussion effect would of course be smaller, but would damage need to be added on to make it useful? Is this reasonable, or would it join the ranks of the unused addons?

Isn't there a concussion rail gun?

There is already a 'concussion flare' that does only 1 damage (might be zero) that is available through Xang Xi in a mission (check sedina k-13, 'Ore Rush Job.) Unfortunately you only get 1 of these, and perhaps the mission should let you just buy them from Xang Xi instead of just getting 1 or 2 for the mission.

The concrails are un-buyable to anyone on the production server (except devs)

theratt10: Can you name any example situations where this would be even remotely useful?

Traders running away. Give the missiles relatively high trigger range, so you just need to get them near the target. Also notice the last sentence asking if you think this is reasonable or if it would just join the ranks of unused addons.

No, that wouldn't useful. If you have ever tried using swarm missiles on a trade vessel, you will notice that you are not able to hit a pirate with them.

Generally, it's a good idea to have some specific reason for suggesting new items. A solution looking for a problem is never a pretty thing.