DNS, I agree with that last post.
The BG's left without the victim having or using a gun, so no gun was enough... in a way.
And for all we know, five of the six were lookouts or drivers or fences.
And the vast majority of defensive uses of firearms result in no shots fired.
But on the conservative side, I'd prefer to have the option of more ammunition, in case there actually are multiple BG's and they don't run. As noted, more ammo isn't helpful if one makes oneself an easy target for multiple shooters; solid tactics are required.
But tactics have to be truly stellar, if one lacks adequate ammunition.