I thought they had bolt guns?
Well for a while they did, but they were always on backorder from Petzl and you could never find them in stock anywhere, so most people just gave up on them. I think there was some part that they were having trouble with and then I didn't hear about them too much after that. That was like 10 years ago.
It's pretty rare to see someone using one these days. I remember when the first ones came out, they used to fracture the shit out the rock. It's rumored that that's why the Texas plate first started coming loose from El Cap.
If you find one of the later ones, chances are that the sleeve bearings in the barrel are shot, which basically ruins it for good. That's what winds up happening to 95% of them sooner or later.
So it's possible that one could turn up on EBay occasionally, but you really want to know the condition.