Starting with 3 pieces of Winchester 30-30 brass that has been fired once previously. Using XMP5744 from a Lee 1.3cc dipper (17.3g) (just under starting load for 190 grain cast bullet), Remington 9 1/2 primers and cast 180 grain bullets gas checked that weighed 187gr after size and lube, sized .309, lubed with Ben's Red and a coat of BLL tumble lubed. Dies used were RCBS Cowboy dies with just enough flair to start the bullet and crimped to the case being just flush with the first band.
I started to think that the test wasn't going to last long when the first neck split at the sixth loading. The two remaining cases were annealed after the 11th reloading. I was beginning to think that they might be indestructable but after the 20th firing both of the remaining cases had hairline cracks at the mouth. Neither case showed signs of stretching and the web of both were still a smooth transition to the wall of the brass.
As a matter of curiosity, I trimmed both to beyond the crack. The shortest of the two measures 2.015", 0.014" shorter than the 2.029 trim length. Both still useable if you were in a bind though probably not the best for accuracy but still well over one calibre for seating depth.
It did make for a fun and interesting day.