in his photo his slide is a 1/4" in front of those back rails, in GB photo his tutorial slide is sitting on the rails( I realize different guns are picutred here to)I would guess maybe 3/8" difference when u compare . I think I would pull the side panel as one suggested to view to see if that is indeed locking the slide and proceed then either way. I guess I am still undecided if indeed it is the cocking cam causing this as the position of his P380 slide at least to me does not indicate that. If the trigger is moving freely would that not indicate that the cocking cam is moving also??
removing the side plate will allow u to look at what is going on but with the trigger bar in place that will not come out through the side plate, without removing the trigger parts, u cannot remove the cocking cam or any parts. U might be able to manipulate that cocking cam if that is the culprit but like Gregg stated u have to be able to move that slide a tad to allow the cocking cam to move, if the slide is locked that tight on the cam, then some force is going to be needed. I also think the reason the slide will not move one ioutta backwards now is that it is now forced back so far that the slide stop pin is now lodged right behind the barrel lug and the only way the slide can move now is forward. It just cannot move any further backwards...
In my opinion, unless some real forward force in applied to the slide, with trigger pulled and kept that way, the gun will need to go back to kahr, as quite possably some parts might even be damaged in trying to force the slide off the gun anyways. It's unloaded, it is safe to mail.