Yes those and the rifles labeled the same back during the Brady Bill days are perfectly legal to own. Unless you live in one of the Socialist Anti Second Amendment Gun Grabber States here in the USA! In fact the AR-15 Semi Rifles that have the markings on them are collected by a few people. If your state does not for example have a ten round magazine rule restricting the weapon to only 10 round max in a magazine you are good to go!
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