I picked up a real cheap one ($5) in my early years of gun hood... it has never even fed the whole magazine... and I have 3 1911s...
First, the feed lips are not spaced correctly, so the round is not high enough to be picked up by the slide. (Opened it up)
Second, there are tons of burrs that catch the follower and rounds when loaded. They get stuck and don't come up without help like being shaken or poked at. (Dremel tool at work)
Third, weak, weak, weak spring. The slide was closing before it was even getting the next round up.
I might try a good Chip McCormick or Wilson 10 rd mag, but never another cheapo 15 rounder. I have plenty of 8 and 7 round mags now anyways... good ones.