Comets are the most pristine objects in the solar system and exist primarily in the Oort Cloud and the Kuiper Belt. They are composed of ice and dust in roughly equal amounts with the ices being primarily composed of water but also containing complex organic molecules. Due to their composition, comets are potential candidates for the origin or water and organic molecules on Earth. Chemical studies of cometary ices are somewhat scarce, so it is important to develop this understanding of ice chemistry both in its cold early life and its more active phase. Our chemical kinetics model called MAGICKAL is the most advanced interstellar ice chemistry model and the only cometary ice chemistry model. MAGICKAL is the first model of its kind in treating the primarily UV and Cosmic Ray driven chemistry of cold storage cometary nuclei. Cosmic rays are a notable source for chemical change, both in the loss of volatiles as well as the production of complex organic molecules through radiolysis. In addition, while not a significant factor in Kuiper Belt or Oort Cloud orbits, solar UV and protons become much more important during the active phase. Further, external energetic events during a comets cold storage could cause unexpected chemical processing of cometary ice, such as through supernovae or passing nearby hot stars. All of the above can significantly affect chemical processing in both long term and short term and has implications for both modern and ancient comets. Two such comets in particular have received a fair amount of attention: Comet Hale-Bopp and Comet 67P/Churyumov?Gerasimenko. Both of these comets are quite different in their histories and conditions, and they serve as foundational studies for chemical ice simulations through the use of MAGICKAL. The results and effects of varying conditions and processing are presented.