I want to say the Diablo came out around 1994 or 1995.
It was made by CMI but sold through NPS. I've owned several of these and they're fairly standard for Nelson Clones; they work just like the Empire Trracer. I don't remember it having any kind of detent system, so you're going to want to use tape or nail polish in the barrel. The "anti-double feeding system" mentioned in the picture refers to the way the trigger locks the bolt forward when you cock it. The barrel is quite heavy and isn't compatible with anything besides other CMI guns.
The gun is probably worth $40-$50.