Wait a minute, you said you replaced the extractor spring with HD Wolf...AND an O-ring? I think one or the other would be enough. I know the extractor pressure should'nt have much to do with your bullets jamming below the ramps, but, did you have the problem before that? It is not hard to do your own M4 ramps with a dremel. I have done it numerous times with no problems, it always fixes the failure to feed. Just dremel what is necessary, look and see exactly where the nose of the bullet is hitting, and check both the left and right ramp, and polish and blend the ramp where it needs to go, just a little at a time and staying with the shape of the current ramp. DO NOT do this if you are not comfortable, I'm just letting you know that it is common practice to fix this problem. But I would take some tension off of that extractor first, it's unlikely, but if it worked before?