Patent ID: 8443886

Claim:
An apparatus for use in perforating a wellbore casing, comprising: a tubular housing including a first end, a second end, and an internal cavity between the first and second ends, wherein the internal cavity is adapted to contain at least one perforating charge; a first end cap that is positionable generally adjacent the first end of the tubular housing; a second end cap that is positionable generally adjacent the second end of the tubular housing, wherein the first and second end caps are respectively interconnectable to the first and second ends of the tubular housing such that the tubular housing is rotatable relative to the first and second end caps; a first bearing structure positionable generally adjacent the first end of the tubular housing, the first bearing structure including a first portion that is non-movably interconnectable to the tubular housing and a second portion that is non-movably interconnectable to the first end cap; a second bearing structure positionable generally adjacent the second end of the tubular housing, the second bearing structure including a first portion that is non-movably interconnectable to the tubular housing and a second portion that is non-movably interconnectable to the second end cap; a stub extending away from a first surface of each of the first and second end caps, wherein the stub of the first end cap is receivable within a bore of the first bearing structure and the stub of the second end cap is receivable within a bore of the second bearing structure; a first substantially straight reference line defined along an outer surface of the tubular housing and extending between the first and second end caps; a second substantially straight reference line defined along an outer surface of the tubular housing and extending between the first and second end caps; and a reference plane defined through the first and second reference lines, wherein the first and second end caps are respectively interconnectable to the first and second ends of the tubular housing such that the reference plane remains in a particular orientation regardless of an orientation of either of the first and second end caps when the apparatus is disposed in a wellbore.