finally you even want to take the firing pin out the bcg and wipe it well before firing your first round… in my very strong opinion the most important cleaning is when you first receive the firearm!
fully assembled rifle, no mods.
Yes, standard PSA build
oh… well that’s all i got, wish you best of luck!
Check your gas block and gas tube. Also take a look at your buffer and spring.
I kind of read through the posts but never saw if you told us the when of this happening.
1st round? mid mag? last round?
I think if as you posted you have had this happen with 3 different mags, I would try.
1- lube as others have said, you don’t need to drench it, but a new AR can require a “damp” level of lube compared to say a Bolt gun.
2- try having someone else shoot your AR (to remove you from the equation) preferably someone that shoots ARs
3- change ammo
4- don’t do all 3 at once, you need to know what is causing the issue