3 Calibers To Do Everything

[The Harbor Master]

.22lr
.223
12ga

And a good knife.

 

[EmperorMA]

Easy for me.

.22 cal - .22 LR
.264 cal - 6.5 Creedmoor
12ga

 

[Robobiss]

20 gauge
223
6 creedmoor

In reality everyone needs a 22 as well, but a 20 gauge can do everything a 22 can do aside from cheap plinking, while the inverse is not true.