Originally Posted by
BufordTJustice
There's a lot more than just an extra has vent hole..... Or two. There's also the divergent dual entry holes as the gas enters the expansion chamber. And, also, the altered cam pin track.
It all adds up to more free extraction and less gas energy being spent/wasted tugging at a case that is still obturated.
I haven't found it to allow a full move up in buffer weight, more like half way in between weights. So, if a gun runs marginally with an H2, the e-carrier will typically allow it to run reliably.