Ok, that makes me the polar opposite.
I've cleaned my Rock Island twice in about 600 to 700 rounds. It never had any problems despite all of the crud.
It needed about 50 rounds to break in. I did have a few failure to feeds in that first 50 rounds, but none since.
I think you're right about the magazine sometimes causing the problem. I switched the RIA mag for a new Chip McCormick and had no problems. But I didn't have any more problems with the original RIA mag after those first 50 rounds either.
My experience as well. Mine shoots every pull of the trigger. Only time it wont fire is when the mag is empty. Go figure!