If you're ejecting at around 4, you're short stroking, also known as "not getting enough gas". This would be counter productive to add weight to your buffer or increase the buffer weight. You're not getting enough gas to your bolt carrier for it to lock up, but enough is coming in to eject and cycle the next round.
Two things:
- Turn your adjustable gas block to the fully open position shoot with it that way; see if there's soot/carbon build up after shooting to see if you're getting gas leakage.
- If no gas leakage, then make certain that you're using the correct Buffer Spring (coil counting if necessary, but measure total length uncompressed) and Carbine Buffer.
If you're still using the A2 Buffer, spring and Tube, then that could mean that you are using the right component, just getting some gas leakage from you gas block, or at the gas key on your carrier. Look for leakage there as well. If all seems to be good and no carbon signs on the gas system components, then your port on the barrel just needs to be broken in some with more shooting. If you feel confident in opening the gas port yourself, you could do that as a last resort, but I strongly recommend you have a gunsmith or Faxon handle that for you instead.