If you have an L Series recon with a large bolt sled lock, make sure that the bolt sled lock is not depressed with the slide in the fore most position. In other words make sure the triangle looking spring loaded piece on the back of the rail connected to your breach, aka long tube the dart shoots out of, is up and not stuck down. If you have an A series recon with a small bolt sled lock, just double check everything is seated properly.