You can access all of them in Homecoming mission. Fortunately, there is no struggle in the process. When you start playing the mission in Beta,
after landing on the destroyed The Last City, you will pass injured people. A guard wills open door for you to the weaponry, there you can pick up the weapons. Enter the armory and this is the first time you get some rifles. This is one chance to pick up good weapons before you land into the battle. So below are the three weapons you can carry.