Here are the steps on how to assemble since you did not have a chance to see it before hand.
1-Thread new barrel stud into the bottom of the barrel and tighten firmly.
2-Slide the magazine post over the barrel stud.
3-Install D-clip into the groove on barrel stud. This will secure the magazine post.
4- Install escutcheon, carefully seat into it into appropriate hole with a punch.
5- Thread action screw into escutcheon.
6- Assemble stock to barrel assembly.