Tales from the precision frontier. 

Precision measurements are not only touchstones for validating modern nuclear theory, they also offer a powerful and complementary path to discovering physics beyond the Standard Model by exposing deviations from theoretical predictions. In this talk, I will discuss two experiments that probe the precision frontier: The first is MUSE, the Muon Scattering Experiment, at PSI in Switzerland. MUSE measures elastic scattering of electrons and muons off protons, to address the proton radius puzzle and to test lepton universality and radiative corrections. The second, DarkLight@ARIEL, is a direct search for signatures of a fifth, proto-phobic ``dark sector'' force using TRIUMF's low energy electron beam of the ARIEL facility. This ``X17'' particle is motivated by anomalies measured by the ATOMKI group. I will summarize the experimental approaches, recent progress, and the physics case for both