As you can use AGI to shoot, it could be implemented in the AGI (climbing) check ;-)So... the shooter of the grappling gun doesn't need to make an ranged attack?
My problem is, that AGI(climbing) sounds more like you already have a rope to climb on. As you can see here, the coast guards use modified guns to shoot a rope to ship nearby. I don't see them already climbing....As you can use AGI to shoot, it could be implemented in the AGI (climbing) check ;-)
If the GM wants to go through the process of separating the launching of the line, they can. It's their call. But the system is also setup to just assume it's all part of the same thing.
To me, it's the whole process. You're at the bottom of a cliff with your climbing kit, which includes grapples, ropes, pitons, all that stuff. Your climb check represents you using that equipment to climb.