As of September 2016, medical marijuana card holders do not have the right to bare arms, in These United States of America. Under the rules and regulations of The Bureau of Alcohol, Tobacco and Firearms medical marijuana patients are considered unlawful drug users. In this instance, federal law trumps state level cannabis legalization; while this makes sense in a hierarchy of sorts it is just a bit asinine.
With 24 states allowing allowing state level cannabis decriminalization and 10+ states voting voting on either medical marijuana or recreational marijuana programs, this is going to cause a serious issue. This is yet another major bump in the road for cannabis normalization at the national level and rest assured it will be a major clashing point between activists and lawmakers. Currently in the United States of America there are anywhere from 270 million to 300 million guns, this is an astronomical number of firearms as the population of the USA is 324 million as of 2016.
With that many firearms in the hands of that population, the laws will need to be changed quickly and at a state level, to begin with. With many states bypassing the DEA on its restrictions to medical cannabis research, it will be no surprise when states take control of their own gun owning population, in favor of marijuana and legal ownership of firearms.