Navigation drawer in android is not full screen

Well creating a custom navigation drawer is the best solution for you. I understand you do not want to use third party but this can be a quick solution to your problem Sliding Menu Lib link.

Hope this Helps.

  <android.support.design.widget.NavigationView
        android:id="@+id/nav_view"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:layout_gravity="start"
        android:fitsSystemWindows="true"
        >
        <include
            layout="@layout/nav_header_main"
            android:layout_width="match_parent"
            android:layout_height="match_parent"

            />
    </android.support.design.widget.NavigationView>

Remove the last two lines in the default code

app:headerLayout="@layout/nav_header_main"
app:menu="@menu/activity_main_drawer"

Here is a quick solution that worked for me :

<include
        android:id="@+id/left_drawer"
        android:orientation="vertical"
        **android:layout_width="320dp"**
        android:layout_height="match_parent"
        android:layout_gravity="start"
        layout="@layout/drawer"/>

Set width of included layout . For devices with different screen size you can dynamically set the width of this included layout .

All the best !!!!