The real question may be:
What will be the AMMO of the apocalypse ?
My grandfather and my Dad both owned and shot 38 revolvers.
After the passing of my Grandfather & Father, my brothers and I split everything up.
Between them both, I think there may have been 200 rounds of 38 Special in the bottom of the gun case. 2 boxes of 7mm mag, 3 50 round boxes of 22LR, and some assorted 12 gauge.
When they went shooting, they stopped by the LGS, picked up what they needed for the day, weekend, week and off they went.
The only round I can ever remember my Dad buying in "bulk" was 12 gauge dove shot at the beginning of dove season as we all shot 12 gauges.
Now, I and many others purchase our preferred ammo a 1000+ rounds at a time.
I have more 9mm ammo stashed away than my Grandfather and Dad ever owned or fired combined.
This is just the difference in today and the past.
In the past they never worried about ideological zealots in the government making their preferred firearms or ammo of choice illegal, so there was no urgency to stockpile.
If you look at gun sales and ammo purchases over the last 20 years, I think 9mm, 40 S&W, 223/5.56, 7.62x39, etc... are going to be very common if an apocoliptic situation were to arise.