Beginning to order stuff

[LRRPF52]

Bringing up an old topic. So I got my barrel in that was discussed in this topic.
I wanted to verify that it has an extended length gas port.

How long is an ELGP?
Where are the measurements taken from? Front of barrel extension?

Is total barrel length taken from same location

These pics don't have shoulder dimensions from a reference point, but the ELGS should be ~2" longer than a RLGS. There are different shops that have the gas tubes made for them, and there is no industry standard for an ELGS that I'm aware of, although there seems to be a common use among different custom shops who get their gas tubes from the same places.