My partner has an AR-15 that is givin him fits. I told him I'd through it out to ya'll and see if there's help for him. First, he had a 30rd mag with 25 rds in it. When he loads it, then tries to chamber a round, the round gets stuck half way in the mag. Like the buffer spring is too weak. second. he has a problem with the extractor not extracting ever 30rds on full auto and ever90rds on semi. what I've checked: buffer spring is strong, good shape. Bolt rotates smoothly in the bolt carrier group, not stiff. Bolt carrier group moves freely in the upper reciever. Bolt locks ok. Couple of times I had to use the forward assist to get the bolt to lock, but I think it might be a little dirty. thats all I got for now. I'll update when I find out more. thanks Wanna kill these ads? We can help!