2 winters ago my son was short 243 ammo (I'll not get into it - ex-FIL) on the day of season.
That said - I hit up 4 different places looking for 243 ammo - not a box to be found till the last place. Mom an Pop in a town of about 400 people. Sitting there on the shelf next to 6.5 Creed and 375 H&H Ammo.
243 may be more available but what is available might not be exactly what you want. To a lot of people it's still a varmint gun and that even extends to a few store managers.
Yeah, the 243 is likely more available, but it is absolutely more popular, and every Tom, Dick and Harry, who bought one box last year, used 9 rounds to confirm zero on their Simmons/Tasco and then shot three at running deer will be back this year looking for another box.
If you run the 243, you can be smart and buy a hundred rounds or so and get zeroed, but you can do the same thing with the Creedmoor.
