Those CCI minimags work well in the AA upper. I used them at first for break in also, but I used the 36gr. No worries. Just disassemble the slide, barrel, and lube the heck out of it and she will run. Slow, aimed, supported I had no issues holding a 1" group at 10 yards with a red dot and I'm not a great pistol shooter. After the break in the wife has run a few thousand rounds of Aguila 40 gr thru it without issues as long as I clean it and relube it every couple hundred rounds. I find she hands it off to me to clean or swap the 9mm slide/red dot combo on it for her as she struggles to field strip the Glocks.