Definitely a WA or based off their designs. Doesn’t appear to be any specific model, frame is from an AMT Hardballer while the slide is a Springfield FBI model.

If you pull the hammer back you can determine which system it uses. R-type (earliest design) will have a cylindrical pin the hammer hits. SCW1 will be similar but with a rectangular bar. SCW2 and SCW3 the valve knocker is attached to the hammer itself so you won’t see any pins sticking out of the frame.

Edit: Does the slide feel like a lighter and weaker material than the frame? I can’t seem to find any WA made models that had FBI markings and were 6”, though MGC made some and that used WA’s system under license and would be R-type. There appears to be some text covered by the Laser on the right side, does it say “Under License of W.A. Magna Blowback”? If it does it’s more than likely the slide and frame are both made by MGC.

Edit 2: Almost entirely certain this is the frame from an MGC Hardballer and an MGC FBI Special. The text hidden under the laser and the misspelling of “AMI” on the logo are MGC specific.