Interesting. At one point while playing with one of Paul's chargers I was getting them to lock with 150grFMJBTs at an OAL of 3.03".  At the short length the rim of the second round in the loaded charger would move ahead of the rim of the bottom round.  Occasionally, that position would carry over as the rounds went across the magazine and bang, it was stuck.  But more often they would self align on their way across.  A little tweaking on the charger got them at an angle that #2 didn't jump forward anymore.  Always that first round, I don't think any below it in the magazine were entangled.