So as the OP my thought process is I can get SWMBO to approve a 22lr for small varmit killing.
For 2 leg varmits I have a 9MM in the nightstand. That will take care of the someone coming into the house to rob the place scenario. For reasons not germane to the debate I find that superior to a shot gun.
The desire for the long gun in .223 or 5.56 NATO is if the stuff hits the fan. That will be, in my mind, a far superior weapon than a shot gun. The 30 rd mag and range will make it so in my mind. I also won't care what Indiana law says if I need to take a deer to feed my family at that point. Any scenario where I am hunting for survival food means things are really bad. 223/5.56 NATO ammo is plentiful and relatively cheap (certainly not as cheap as 22LR).
So my justification to SWMBO would have been that I could use the 22LR to dispose of varmits of the 4 leg variety, but still get something to edge toward protecting the family if it hits the fan.
The interchangeable parts to use 22LR do not make sense to me if I can get a good 22LR rifle for the same cost. Having 2 rifles is better. While 22lr is not a good man stopping round if it hits the fan me with the 5.56 and the wife with the 22lr is superior to me with the 5.56 and wife with nothing.
So now I have to figure out how to justify BOTH purchases
Then start to accumulate ammo and some extra magazines.
Everyone thinks that the North Korea mess is what is going to bubble over. I think it is the moving of the US Embassy to Jerusalem that will cause a tipping point. Note I am not trying to start a political discussion, just advising of why I am thinking more about this recently.
It goes back to the recent thread of if you could only have two guns....