some primers known to have a soft/thin primer cup may experience slam fires, especially if not seated correctly into the primer pocket.
with a properly seated primer and a firing pin in good working order it shouldn't be an issue with most types/brands of primers - specifically those used in factory ammo.
if you're concerned with the brand ammo you're using - feel free to test it.
put one round in the mag, lock the bolt open. hit the bolt release to chamber the round. eject. inspect. repeat.
if you're going to go that route i would suggest measuring the OAL beforehand and stop if you see any bullet setback from repeated chambering. this would probably be more an issue for handloads that aren't crimped but may be an issue with factory ammo as well.
personally i reload several AR calibers - 223, 204, 300 blk - with cci 400 SR primers & have since i started reloading ~6 years ago. my hunting loads will often see a half dozen chamberings over the course of a couple days of coming and going from the field on a hunting trip. out of habit i usually stop chambering after around a half dozen, and cycle that round into the bottom of the mag, but i have yet to experience a slam fire under any conditions with the 400's or factory primers, including testing out to 10 chamberings on the same round.
