How does the exit hole on a carrier relate to that of the perforated casing?
It has often been observed that exit hole on a spent carrier while round or nearly round is not as large as the published data suggests. The reason we see this is because of clearance. Which is the distance from the edge of the scallop to the inside edge of the casing being perforated. Charge manufactures perform static QC tests on surface using known carrier parameters including clearance, fluids, carrier wall thickness and scallop depths. This data approximates everything that the shaped charge will encounter in a real well situation and is recorded as QC or quality control data. In the above case we see what the charge saw as it exited the carrier and not what the casing experienced. Depending on what type of shaped charge you are dealing with the jet stream may still be developing as it exits the carrier and before it reaches the casing a nanosecond later.
