Its really luck of the draw with Century. Sounds like you have one of the franken-fal's that's a mix of metric and inch parts. I have one of the G1 builds from them and my only issue is my gas port in the barrel is a bit too big. I'm not aware of any after market sights or a way to lighten the trigger. You could get some railing and put whatever sights you want on it. The design of the trigger doesn't lend itself to lightening easily.