are first loosened in order to allow the charge tunnel housing 44 to move laterally optionally as discussed below the fasteners 104 may be used to adjust the charge tunnel housing 44 in vertical directions a channel 108 extends horizontally through the upright member 50 and allows a fastener 110 to pass therethrough the channel 108 is aligned with the channel 84 of the charge tunnel housing 44 and the cavity 80 of the charge tunnel unit 68 a spring 112 is disposed within the channel 84 and abuts the charge tunnel unit 68 around the cavity 80 a distal end of the fastener 110 is disposed through the spring 112 and abuts the charge tunnel unit 68 through the cavity 80 the cavity 80 may be threaded and a distal end of the fastener 110 may threadaby engage the cavity 80 when the fastener 110 is tightened the fastener 110 extends further into the cavity 80 in the process the fastener 110 draws the charge tunnel housing 44 toward the upright member 50 in the direction of c u2032 as the fastener 110 is loosened the fastener 110 recedes from the cavity 80 the spring 84 elongates and the charge tunnel housing 44 moves away from the upright member 50 in the direction of arrow c u2033 the fastener 86 may be engaged to move the charge tunnel housing 44 as well additionally the fasteners 104 may be engaged to adjust the charge tunnel assembly 66 in vertical directions denoted by arrows d for example when the fasteners 104 are tightened the charge tunnel assembly 66 may be drawn upward in the direction of arrow d u2032 by way of the fasteners 104 engaging the threaded through holes 82.