After examining all 19 of my intact Scourge missiles under magnification, I have come to the following conclusion: There is only ONE variant: Three piece, With two versions: Glued properly, and not glued properly, if at all.
(Editor's Note: Initial-release of Scourge had headguns that could seperate into their three individually-molded pieces. The second-wave semi-secured either the back or the front of the mold [depending on the mood of the factory-worker that day]. Later versions were glued properly, leaving the weapon, for all intents and purposes, a single piece.)
This can easily be seen as true [on the solid ones] by flexing the rear pin on any Scourge missile under magnification. The gap between the back of the center piece and the start of the groove for the back peg widens enough to see the seam (in most cases.) It is impossible to apply enough pressure to the front end to see the joint without damaging the piece. I will be sacrificing a "solid" one to the exacto saw, to prove this point.
(Editor's Note: Another easy way to tell is the mold fill/removal points on the missiles. You might note that they don't line up on the underside, as they should if they are cast in one piece.)
(Joebot continues his experiment)
The sacrifice has been made. Pics are uploaded. I used a vise and vise grips. Please note the evenly machined edges are deeper than the visible outer grove, and indented in such a way that the part would be impossible to remove if the piece were cast as a unit.
Pic 1: A solid-piece, before I attack it with my pliers:
Pics 2 and 3: Look at the molds on these pieces:
Pic 4: Look at the center piece of the now-not-so-solid gun:
Pic 5: A 3-piece gun that comes apart easily. Compare it to the previous pics. Notice any similarities in the molding? :-)
Hope this helps to solve the mystery. One missile, three pieces: glued firmly, or poorly glued if at all. Pity me. I am one Scourge head missile less... So, who the heck is still casting parts anyway? And more importantly, do they give bulk discounts?
(Editor's Note: Heheh. Here are some further scans of intact Scourge missles, type 1 and 3 comparison-close-up.)