Those with an extra supply of guns, ammo and magazines have the wherewithal to arm other people they trust. Ya gotta plan ahead more than One magazine.
Trustworthy, competent, and wealthy friends and relatives would be extremely valuable in a lengthy bad situation. By wealthy I mean "in possession of valuables". This could mean food, medical supplies, and other survival equipment.
Such people are not necessarily acquainted with firearms and may be invited despite that lack if they have other redeeming qualities.
Having a critical mass of people capable of guarding what you have and foraging for what you need would enhance survival chances immeasurably. You want other people to underestimate what you have and overestimate what you are willing to do in order to keep it.
Make sure that you are not the easy target. I recall from my time in the military that there was some value in having people think that you are just a little crazy.