Differential Stroemgren uvby observations from the Four College Automated Photoelectric Telescope (FCAPT) are presented for the mCP stars 20 Eri, HR 1297, 12 CMa, and HD 134214. Adelman & Boyce found suggestions that the light curves of 20 Eri change between observing seasons. Observations for two additional seasons confirm this behavior and lead to an improved period of 1.928890 days. For HR 1297 a new period of 15.7490 days was derived. The uvby light curves now appear to be the same for different observing seasons. 12 CMa is found to be a photometric variable with the 2.18010 day period determined from magnetic measurements by Bohlender et al. Observations of the rapidly oscillating Ap star HD 134214 confirm the lack of photometric variability which is not associated with the rapid oscillations.