I don't have a cheap AK. Its a milled one, forget which one. Have never had single failure with it. Other than the accuracy failure issues. LOL.
That said I've put way more rounds through ARs, wife and I generally ran 20 k give or take for 15 or so years....
I"ve seen really few AR failures from well built ARs. And lots were ammo/mag issues not gun issues.
I did see 2 with broken locking lugs... drop a new carrier in asap and back up and running. Some were issues with worn gas rings, that was failure of maintenance.
Occasionally a loose primer pocket would drop a primer into the trigger group and lock it.
But for all the rounds I"ve seen shot, reliability of the AR has never bothered me.
