Can anyone help me with this question?
OK, I'm not a gunsmith. You need to figure this out for yourself. This info might help. YMMV
If there is already a channel liner installed, you will not be able to insert a second one. Try to insert one with the tool by hand. You'll know if it's going in or not. You can't install 2 channel liners and the striker assy in an upper. They just won't fit.