That’s how I store my mags, 29 rounds, learned that from old Vietnam vet.
My late father-in-law shot the 1911 all the time. He went into the Air Force and left several 1911 magazines loaded at his parents house while he was in the service. Four years later he was discharged and he returned home briefly before moving out and found his old fully loaded 1911 magazines. He went to the range, slapped them in his 1911 and they all worked without a hiccup.