My VZ2008 has an issue with feeding/cycling. Before I even shot it, I thought that the bolt carrier moved awfully sluggishly. Fast forward to its first range outing, the bolt carrier didn't have the strength to fully chamber the first round. I've observed that the first 5-6 rounds from a fully loaded magazine struggle the most (when the spring tension is highest in the magazine). Once I get below 22-23 rounds, the rifle cycles much more reliably, but still has hiccups now and then. Since I don't get to go to the range a lot, I figured I'd just keep shooting it and try to wear it in. 400 rounds later, it cycled noticeably more reliably, but still would have trouble pushing the next round into battery sometimes.

Upon taking it apart, I don't really see any wear marks anywhere. What could be causing this?