Shiveluch Volcano is a highly explosive arc volcano in Kamchatka. A previous petrologic study of mafic enclaves at Shiveluch showed that primitive magmas in the lower crust have 9-11 wt% H2O at depth (Goltz et al., 2020). The study also suggested that andesites stored at upper crustal conditions are produced by fractionation of near-liquidus amphibole, olivine, and clinopyroxene in the lower crust. To test this hypothesis, we determined the liquid line of descent of two primitive Shiveluch magmas by conducting equilibrium piston cylinder experiments at 1 GPa and 500 MPa with varying volatile contents. We find that only water saturated experiments reproduce the hypothesized early fractionating assemblage of amphibole, olivine, and clinopyroxene. However, we also find that all experimental glasses are higher in Al2O3 than andesites erupted at Shiveluch and thus that fractionation alone cannot produce these more silicic compositions, a conclusion supported by other recent experimental studies of lower crustal differentiation (e.g., Blatter et al., 2023; Marxer et al., 2023). Additionally, experimentally produced amphiboles are higher in Al2O3 than amphiboles from natural samples at Shiveluch. Here we evaluate several scenarios to reconcile the experiments with natural variations and compare this to other arcs worldwide.