Though not a prediction of total life expectancy, I usually retire my cases after 5 loadings for the AR platform. Two reasons:
First, the sized cases shrink in length after each firing though the most occurs after the first firing. Once a case gets below 1.680 it is retired. The chamber is cut to headspace the cartridge at 1.70. If you've ever looked at what constitutes a solid NO-GO measurement, its a lot less than .020 inches. Luckily, at the pressures we use, the 450b is more forgiving than bottleneck calibers.
Second. This is particularly important if you like to load them at the top of the charts. The case head grows in diameter. The resizing die only goes down so far and in my chamber, once they grow more than .5017 in diameter, they get either stuck going in or coming out of the chamber. In this image, you can see the scuff ring where CHG is most problematic. That's just above where the web transitions to the case wall.
Notice the micro dots in the extraction groove? I add one every time I reload.
Here'sThe Link to the article on how to make one of my "sproinkers" for applying the dots. They don't interfere with chambering and unless you eyes are goners, you can see them without magnification. I mention this because you really should anneal them after every 5th reloading to keep the neck area from hardening too much. They won't split like some bottleneck cartridges but it does impact how much of your taper (or FCD) crimp springs back.
Anyway, that's my philosophy on how many times I reload cases. If you've been feeding them a
spicy diet, that can occur in as little as 4 or5 reloadings in terms of CHG. As far as length shrinkage goes, my experience has been that a repeated diet of lite loads causes them to shrink the most. I don't need a bolt action or single shot rifle since I'm pleased with my AR variant, so I can't comment on case life expectancy in them. I do recall one of our early bolt action adopters saying he has gotten as many as 20 cycles out of his brass from his re-barreled Mauser 450b rifle.
Hoot