Occasionally my StG58 will double and I have written it off to a loose hold resulting in a bump fire but today it ripped off a 3 round burst with some very stout 600 yard loads.
Not much fun when you are not expecting it although it did get everyones attention.
I added a US made trigger when I had the FH put on and that seems to be when the problem started so I am going to put the original trigger back in and see if that clears it up.
I have a Tapco gas piston I can add to maintain the parts count.