There will be no military force in peacetime. We are a non-imperialistic state, and will only fight as a last resort in protecting our home. This being the case, any citizen wishing to own a weapon above a certain rating, will have to first complete some basic military training. This may be as extensive as a month of boot camp, or something like the Army Reserves. Each level and category of weapon will have an additional segment of training to assist in its proper use.
There will be a cadre of officers who are full-time military men, but it will be a small group, and mainly deal with the development of training and strategies that will best utilize our home terrain.