So here's that thread,
@Alex!
There are those who suggest consolidating ammo / calibers to make things simpler. Make all your guns 9-mm for example. 9-mm pistols and 9-mm carbine rifle. I guess that will work if you have a LOT of that particular ammo in your inventory. But what if you're on the move? You can't carry your entire inventory. What if you run out of ammo on the move? Will you be able to find that caliber "out there?"
Personally, in case of zombie apocalypse, my plan is to "bug in." Nevertheless... over time, do I want to be limited to one caliber and risk it not being available? I think diversification is a better strategy.
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I will be adding 10-mm to my "stable" of calibers in the future.
I also need to replenish my ammo after the scamdemic drought, during which I actually increased my ammo use due to this blasted building hobby!

Rather than conserve ammo during the shortage with fewer range trips, I depleted my inventory quite a bit. DUH! I also shot down my 6.5 Creedmoor supply (for example) while it was simply unavailable or crazy-expensive in the last few years.
In the end, this is likely more about how to stay supplied during an ammo supply drought than it is the zombie apocalypse.
What is your philosophy or strategy?