he's right when he says they've got some quality control issues in their past. just google.
its a budget priced product, so that savings has to come from somewhere - usually either in material quality, or in the QC department, sometimes both.
that doesnt mean they dont produce a good product much of the time, but like many other things in the firearms world - you do often get what you pay for.
that said since its a 1:7 twist, i'd lean towards heavier offerings (>55gr) to take advantage of that fast twist rate.
are you a reloader? or only shoot factory ammo?
what do you plan to use the upper for? hunting? range toy?
that will help folks give you someplace to start at least.