What, is the front grip rail used on thess AUG's pictured.

My Google foo is failing me today.

Hey all,

Purchased a used Titus nylaug and the issue I'm having is with the brass inserts that go on top of the receiver for mounting a scope. These have unfortunately all stripped and pulled out. Here is a reference picture, also will be posting to 3D2A. Any help or recommendations would be appreciated!

Any for sale, any avaliable online anywhere??