The present invention discloses a wellbore subassembly with a perforating gun. The wellbore subassembly includes a tubular body and a perforating charge. The tubular body has a wall defining an interior space and an exterior space and the wall has a cavity. In some embodiments, the cavity may be shaped to define a charge socket that receives only a single perforating charge. The perforating charge is configured in the cavity at a location inside the wall. The perforating charge is configured to discharge toward and into the interior space and penetrate into the exterior space by perforating the wall across the interior space from the location of the perforating charge.