Frustration. If I were you, I would pick up some other ammunition and see if it will feed. If it does, the 'tiger' brand isn't much punk. If it also doesn't feed, start looking to see why.
Is the upper new? If 'new', it will take a few rounds to seat in. I think this is actually a good thing, I think it makes for a tighter fit.
Also, when 'mountainman13' asked if you "oil her up", he/we mean running the BCG 'wet'. It may 'spit' a little but they run better wet.
Good luck and get her going.