SAR-3, when I went to shoot it the first time, the trigger would not function. Would not trip the sear. Apparently, no one at the factory tried it. The problem was the trigger space in stamped recever wasn't quite to spec, and the trigger would run into interference on the receiver before it went far enough to trip the sear. I filed the opening out, and then it would shoot fine.
It was assembled a bit crooked, and I had to move the front sight post quote a bit to the right to get the sights on. Sight picture is kinda funny.
Other than that, I really like the gun...
Second try, a CETME. This one was also assembled a bit crooked, and had the infamous "not enough windage" problem. (Seeing a pattern here?) Even with the windage maxed out on one side, it was not enough to get on target. It was about 6" off at 100 yards.
I was ready to return it, but the retailer had a 'smith who built me a new font sight post with more windage, and that got it on. Again, the sight picture is a little funny.
I also had a problem with it dropping mags while shooting. Turned out to be a burr on the receiver (seeing a pattern here?) that prevented the mag catch from seating fully. Once I filed that burr off, mags function properly.
So, yeah, two out of two were assembled crooked and required some filing of the receiver to work properly. And both require off-center sight pictures to be on target.