When clearing/unloading a firearm always drop the magazine first. There are numerous incidents of AD/ND's as a result of racking slides without removing loaded magazines first. The same rule applies to clearing jams, magazine first then rack the slide to clear jam!Ok, so I burned through way more ammo than I intended to test and re-test. Problem came down to the extractor needing just a little tweak to tighten it up.
What was happening was when clearing the weapon the round was sliding down the breech face just enough to sometimes catch. With a magazine the next round or follower was preventing this.
Kinda happy this didn't come down to operator error but it was something I wasn't willing to rule out. I definitely learned a few things about 1911's going through this.
Thanks to everyone for their insight and wisdom.