The frame looks like a Shadow frame. The slide doesn't have a roll pin which should mean no FPB like a Shadow slide(easy to check if you remove the slide and shoot a photo of the underside of the slide). Shadows don't have a FPB while (most?

) SP01's do. Your slide is unusual because it is not marked "Shadow" and doesn't have a roll pin.
FWIW, when the USPSA Production rule discussions came up recently, I sort of remember someone saying there were regular SP01's out there without FPB. Perhaps this slide supports that statement.
Do all of the serial numbers (frame, slide and barrel) match? Also, could you shoot a photo of the underside of the slide and include the part that says SP01 in the photo?