are sockets 48 for receiving preformed units of shaped charge 40 in the present example the shaped charge discharge axes are aligned in a single plane the loading tube 39 is stepped on opposite sides of a ridge 38 to co axially assemble within the gun tube wall 35 between the ballast rails 37 this ridge confinement necessarily orients the discharge plane of the shaped charge units 40 the mass of the eccentrically concentrated ballast rails 37 provides a gravitational bias to a vertical orientation of the outer gun tube 35 the v channel between the ballast rails 37 keys the annular orientation of the loading tube 39 relative to the outer gun tube 35 the shaped charge 40 may given any desired angular orientation within the loading tube 39 for the discharge axis of the perforating jet 32 relative to the ridge key 38 the relative orientation illustrated by fig2 3 and 4 represents a shaped charge discharge axis 32 that is parallel with a vertical plane however the angular direction of the shaped charge discharge jet 32 about the gun axis may be set at any convenient or desired angle relative to the vertical plane hence the perforation axis of the jet 32 relative to a gravity vertical may be predetermined along the ridge 38 crest is a channel 46 for receiving a detonation cord 44 the shaped charge explosive 41 intimately engages the detonation cord 44 an appropriate example of the invention may begin by contrasting the present invention with the previous example of a traditional 5 in o d steel gun tube 35 having a distributed displacement volume of 0 1363 ft 3 ft and a distributed weight in air of about 14 75 lb ft for a 62 ft 3 well fluid applied the.