Quote Originally Posted by painter777 View Post
Here's a pic of a M2 trigger housing with the right wall cut away and left wall having the notch for a 9 spring. (I'm just trying to be sure your TH hasn't been modified,) I would expect your TH to be a narrow rear wall type II.
See here: The U.S. Caliber .30 Carbines - Trigger Housing Group
The link you put up tells me its the grooved wall. I saw no cutout on the right side for the M2. You know stuff I don't even know to look for.