The F1 Illustrator premiered at the 1990 Master tournament used by Scream (which became Aftershock after merging with the Lords of Discipline). This F1 is likely from later 1991 since it has a 3K serial number. The F1 didn’t come stock (at first at least) with an RVA (Rear velocity adjuster), so the RVA was a popular upgrade early on.
I purchased this F1 on craigslist recently with a variety of barrels. The neatest barrel is the Lapco Nickel plated Bull Barrel.
The Lapco barrel was likely made while Colin was manufacturing with Paintball Connection in San Diego and during this period he, along with many other manufacturers were purchasing WGP bull barrels in different threads and having them cut with their signature patterns.
The interior of the end has the standard Lapco muzzle break step cut as well.