Any steel cased Russian ammunition
Any steel cased Chinese ammunition
Chilean 7.62mm that is marked "NATO"
Cavim 7.62mm from Venezuela
CBC 7.62mm from Brazil
Indian 7.62mm from State factory
1970's production Israeli 7.62mm Browning machinegun ammuntion
Funny, my Century FAL (all metric) ate thru 500 rounds of the "Cavim" stuff in one sitting, and another session with 300 rounds of early 70s Indian surplus. Only issue was getting the gas plug out for a cleaning, but that has happened since with new production Winchester white box, Privi, and some Port. surplus as well...
DSA wants people to stay well within the comfort zone. They do not want people to engage in torture tests with their FAL's because if something goes wrong, i.e. the gun is damaged after a bad round or the shooter is injured, DSA is the one that is going to be on the hook or get sued, not some overseas ammunition company. There are many things you can do but are not recommended...
I can't speak about the "Cavim" stuff, but I have heard of numerous problems with the Indian ammo. -The problem is if an individual shoots 500 rounds of something and gets through it, the person may think it is good to go when in reality 500 rounds of anything is a statistically insignificant sample. The military shoots tens of thousands of rounds when it wants to test a platform or a round.