As a matter of fact this paragraph only seems to give rights to allow those who “
legitimately hold authority” to have a gun, and then again only for the purpose of repelling
"aggressors against the civil community." So the way I interpret this paragraph, it gives the government the right to issue guns to people it feels are appropriate (such as police officers).
Interpreted slightly differently, one would suggest that store owners ‘legitimately hold authority’ to protect their employees. Still a looser interpretation would hold that a parent would ‘legitimately hold authority’ to protect their family.
The first line of this paragraph reads: *"**Legitimate defense can be not only a right but a grave duty for one who is responsible for the lives of others." * And this is the line that seems to support private gun ownership for self defense. Because there does seem to be evidence in other areas that parents/fathers are responsible for the lives of others since they are responsible for their families/children.
Much earlier on in the Catechism, when speaking to civil authority it writes:
1907 First, the common good presupposes
respect for the person as such.** In the name of the common good, public authorities are bound to respect the fundamental and inalienable rights of the human person.** Society should permit each of its members to fulfill his vocation. In particular, the common good resides in the conditions for the exercise of the natural freedoms indispensable for the development of the human vocation, such as "the right to act according to a sound norm of conscience and to safeguard . . . privacy, and rightful freedom also in matters of religion."27
**
1909** Finally, the common good requires
peace, that is, the stability and security of a just order. It presupposes that authority should ensure by morally acceptable means the *security *of society and its members. **It is the basis of the right to legitimate personal and collective defense.
**As a basic human right is the right to live, and as self defense is actually considered a grave duty, it seems reasonable to intuit that we can use ‘arms’ to protect our lives and the lives of our families as well as to protect society. As guns are the most efficient ‘arms’ it seems reasonable to presume that guns are allowable.
It is also clear that we are free to choose our own government, but that government is not legitimate if it forces its will onto citizens.
1902 Authority does not derive its moral legitimacy from itself.
It must not behave in a despotic manner, but must act for the common good as a “moral force based on freedom and a sense of responsibility”:21
A human law has the character of law to the extent that it accords with right reason, and thus derives from the eternal law. Insofar as it falls short of right reason it is said to be an unjust law, and thus has not so much the nature of law as of a kind of violence.22
1903 Authority is exercised legitimately only when it seeks the common good of the group concerned and if it employs morally licit means to attain it. If rulers were to enact unjust laws or take measures contrary to the moral order, such arrangements would not be binding in conscience. In such a case, "authority breaks down completely and results in shameful abuse."23
1904 "It is preferable that each power be balanced by other powers and by other spheres of responsibility which keep it within proper bounds. This is the principle of the ‘rule of law,’ in which the law is sovereign and not the arbitrary will of men."24
Reading the last paragraph is almost like reading an endorsement for the US system of government with its Constitution as a basis that prevents the “arbitrary will of men.”