Recently purchased the Gamo Swarm Fusion 10x Gen. 2 in .177 caliber. Replaced the rear screw with a 2.5 x 12mm screw from the local Ace hardware store. Yes, this rifle's trigger screw was a 2.5mm diameter, not a 2mm. They only had it in a 12mm length, but that works just fine. Loctite 242 on it...