I started having this issue today. I had 80 at the time and 3 more who were just born a while ago. All of my dwellers for the most part, have weapons. I just sent one of them out on a mission just to find more weapons and clothes for my vault. The moment she left to go out, the game suddenly froze. I have uninstalled twice, reloading my Cloud and even restarting my device twice. Still gets the same results. I am stuck on the loading screen with the 'power' symbol where one of the energy rooms are, in a half-tapped icon on the top. I don't know why this is happening, but I don't want to be waiting at least three days or so, just to find out my dweller Piper is dead. I sent her off with at least 15 each of stimpacks and radpacks, so hopefully she'll be okay with that 20-25 hit weapon she got on her at least for a while...
I am using an Android Droid.
I am currently in 1.3
I usually uninstall and re-install to save some MB's.
I manually update the game from the store.