Your job as group leader is to bring out and to take advantage of the talents of others. You are not their mommy and daddy that stand ready to protect them from the harsh realities of a crisis. Your job is to keep the group operational and mission oriented. Your mission is to survive the crisis and the days after, and if so inclined help those less fortunate, and we do not mean less fortunate by choice but left helpless by circumstances out of their control. You will know the difference when you see it.
You should bring people together and this does not mean that you are all clones with the same thoughts, opinions, and ideas. You need talent, because you don’t know everything and if you do, then you are doomed to fail before you even get started. Embrace ideas, be willing to change and have the confidence to make a decision based on the facts and not on your ideology or long held beliefs. Times change quickly, and you have to change quickly as well sometimes or you are rolled over.
There are as many opinions on what you should carry as there are people that carry, but right now the only opinion that matters is yours. In an ideal world where money is no object and everyone is well trained and can pick up any firearm and be proficient with it, you have options. The reality of it all, however, is that most people that come to the group, come with limited training or none at all, and yet they own a handgun, and/or long gun. The fact that someone owns a firearm in no way indicates expertise with said gun. It is your job to find out, however.
Things that you need to consider include ammunition availability. You will not be able to run out and buy more Ammo so you will have to procure it elsewhere. Therefore, choosing the most common calibers will benefit you in the long run.
An alternative, of course, is to load your own ammo, but then you still need supplies that would be in short supply during a crisis. The group may have to share ammunition, so keep this in mind. The time for training and …