Coarse particles of the high explosive RDX in different qualities (S-RDX, I-RDX, VI-RDX) were aged artificially in air and argon, equivalent up to 25years at 25 degrees C. The samples were investigated by means of X-ray diffraction and rocking curves, revealing the behavior of microstrain during the artificial aging. The investigations revealed that the improved crystal quality of RDX survives artificial aging in contrast to a standard quality, where aging increases microstrain significantly. Besides aging details and mechanisms on a crystal level are described and discussed, such as eutectic mixtures with HMX impurities, crystal growth, defect healing, surface diffusion and smoothing, and reconstruction of crystal faces, edges and corners in rounded particles.