For what it's worth, on my first shoot with my 10/22 I picked up 2 Butler Creek mags from Home Hardware and ran them through my rifle. One performed flawlessly, the other wasn't pushing the front of the bullet up to clear the lips and would jam every 5 or so rounds. I tried a couple more times with the same result, marked the mag and returned it to HH. They were good chaps about it and let me exchange it, and I haven't had an issue with the new one.
tl;dr check your rounds for mashed heads because they might not be feeding properly.