how do i make the sentry from portal be in its open position?

how do i make the sentry from portal be in its open position?
it shows its open position in the spawn ghost, but i dont know how to make it in open (like ready to fire)

Maybe a skin or body group.
Body group is more likely.

and how would i go about doing that?

I know there is a Lua function for it.

is the addon from garrysmod.org bodygroup changer work?