Of the top of my head I believe Vltor and Rainier Arms have an upper which has a Dust Cover or Ejection Port Door Cover and without a Forward Assist. I am sure there are some others.
The Constitution is not an instrument for the Government to restrain the people. It is an instrument for the people to restrain the Government!
Today, we need a nation of Minutemen, citizens who are not only prepared to take arms, but citizens who regard the preservation of freedom as the basic purpose of their daily life and who are willing to consciously work and sacrifice for that freedom."
-- John F. Kennedy