The text that you're criticizing is definition of the "The militia of the United States." In addition, each state and territory has its own militia with its own definition thereof. (The US Constitution calls these the "Militia of the several States.") Usually, the upper age limit is in the 60's or 70's. So, you can be a member of your state's militia without being a member of "The militia of the United States."
Regardless, the courts have rules that all competent, law-abiding adults can keep and bear arms regardless of militia (organized or unorganized) membership, with few exceptions. For example, in some states, women are excluded from the state militia. However, in no state is a woman prohibited from posessing a firearm based soley on her gender.
I interpret the age range of “17 to 45” as being the compulsory age to be ready to serve, not that people outside that range cannot serve.
The militia of the state shall include all able-bodied citizens and all other able-bodied residents, who, in the case of the unorganized militia and the Missouri reserve military force, shall be more than seventeen years of age and not more than sixty-four, and such other persons as may upon their own application be enrolled or commissioned therein, and who, in the case of the organized militia, shall be within the age limits and possess the physical and mental qualifications prescribed by law or regulations for the reserve components of the armed forces of the United States, except that this section shall not be construed to require militia service of any persons specifically exempted by the laws of the United States or the state of Missouri.
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The U.S. Constitution acknowledges the Right to Keep and Bear Arms -- and regardless of a liberal saying the 2nd Amendment is "only for hunters" (where is that?) or "members of the military," the fact remains that anyone over the age of 17 and not more than 64 is considered part of the unorganized militia per Missouri law.
Thus, I have an obligation to my fellow citizens to keep and bear arms. I firmly believe concealed carry to be within that realm in order to fight terrorism and those who would cause mayhem.
Some of our fellow citizens need to wake up!!!