I think either lower the dps on the Riflemen or give grenadiers a buff for a fighting chance.
Grenadiers
-Versus Conscripts
Advantaged at long ranges
Even at mid ranges
Disadvantaged at short ranges
-Versus Riflemen
Slightly disadvantaged at long ranges
Disadvantaged at mid ranges
Disadvantaged at short ranges
I'm quite sure they are not supposed to have fighting chance vs rifles. Sole reason is, USF have nothing else in the early game, they can't support themselves with snipers or HMGs or mortars, if rifles didn't walked over grens, then mainline infantry spam from faction that have early and wide access to support weapons would be as strong as mainline infantry spam from faction that doesn't have any other option, which doesn't sound balanced in any way.