A downhole sand control completion system includes a completion string extendable within a wellbore and including one or more sand control screen assemblies arranged about a base pipe, each sand control screen assembly including one or more sand screens positioned about the base pipe. A shunt system is positioned about an exterior of the base pipe to receive and redirect a gravel slurry flowing in an annulus defined between the completion string and a wellbore wall. A return tube is positioned about the e