Required Accomplishments: 2,000,000 Damage repaired (is this type of accomplishment possible? If so, the Repair Gun MkII should have a similar one).
Required Licenses: 4/-/4/-/-
Repairs: 600-5100 hull
Velocity: 220m/s
Charge Rate: 110/sec
Grid Usage: 10
Mass: 2000kg
Ammo: 20

Obviously the accomplishment type would have to change if it's not possible to get damage repaired. Maybe a mission in which you have to make sure something(s) get out of a fight alive by repairing it/them?

The stats are open to suggestions as well. :P

I'm not sure why you felt the need to add grid usage, other than just for the thrill of it. A repair gun is already balanced by:
1) needing to charge
2) huge mass
3) inability to do real damage
4) very low availability

We do need a more useful repair method, but this is just a new face on the old, poor design.

How about making it not need a charge time?

How about making the projectiles homing? It's pretty hard to repair a ship in combat.