I have to concur with everyone else. I have never had a problem with any of the AR-15/M-16A2 models I've fired, and once you know the weapon cleaning it is very easy. Even after range work, a few passes of the bore brush, some oiled patches, and a quick wipe down was all I've ever done until I was done shooting, and then an old bore brush on the locking lugs will remove all the crud in about 5 minutes. Complete cleaning shouldn't take more than 45 mins.
The only time I've had a jam was due to a magazine that was worn out. As soon as I replaced it the rifle never had a problem. I've found that the steel ones can take a bit more abuse than the aluminium ones, but if its worn out replacements can be found almost anywhere.