Which combinations of barrel, rail and gas systems do you prefer?
This is somewhat complex and is going to probably elicit lots of different points of view, etc...
1. Which operating system do you prefer in a carbine with 16" barrel?
2. What do you think is the ideal length of rail? Or what length of rail do you prefer?
3. If you had a choice between an FSB upper or flip sights which would you prefer. Taking into account that the FSB is the most secure and solid of the two.
I am asking this for specific reasons that will become evident later.