I’ve always loaded my 7.62mm AK mags with 30 and now I’m doing that with my 5.56mm Bulgarian mags. I’ve never had any problems with feed reliability in either, though I’ve only had the 5.56mm for a month and only have 1,200 rounds of experience with it. The impression I’ve developed over the years is that it’s just USGI AR mags that are dysfunctional when loaded to advertised capacity, but I was wondering if that is true.
Because of the way they lock into the rifle, you don’t have an issue inserting a loaded mag into the rifle with the bolt forward, and I’ve never, ever seen a failure to feed do to loading to capacity.
I’ve recently used Chinese magazines that I know have been loaded to capacity with Chinese ammo since 1986, and they fed and functioned 100%.
No worries.
Stick with foreign military magazines, avoid the US commercial ones and you’ll be fine.