Android SeekBar Length Doesn't match layout_width value

I am trying to make an anchor width search bar in my layout, however, once the finder barcode width exceeds a certain value, the search width will not reflect the value I set. For example:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
    <SeekBar
        android:rotation="270"
        android:id="@+id/volumeBar"
        android:layout_width="50dp"
        android:layout_margin="1px"
        android:layout_height="wrap_content"
        android:layout_centerInParent = "true"/>
</RelativeLayout>

      

        
        
        
      

    

creates a short search bar as it should, as the width dictates that it should only be 50dp. Here's the layout:

Now when I change the layout_width to 300dp I see a cropped breaker, which is of course not 300dp. Heres file and layout:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
    <SeekBar
        android:rotation="270"
        android:id="@+id/volumeBar"
        android:layout_width="300dp"
        android:layout_margin="1px"
        android:layout_height="wrap_content"
        android:layout_centerInParent = "true"/>
</RelativeLayout>

      

        
        
        
      

    

Note. ... It looks like the width pointer is limited to the width of the relative layout (red rectangle) and anytime the arrow length (given by android: layout_width) exceeds the width of RelativeLayout the length of that length is limited. How can I make my search bar obey my desired hardcoded length?

Edit: I've included the parent activity xml file below.

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent" 
    android:orientation="horizontal"
    android:baselineAligned="false"
    android:keepScreenOn="true">

    <LinearLayout    
        android:layout_width="0dp"
        android:layout_height="match_parent"
        android:layout_weight="1.25"
        android:background="#ffdd4c4f"
        android:orientation="vertical" 
        android:id="@+id/toolbarGestureOverlay" >
        <android.support.v4.view.ViewPager
            xmlns:android="http://schemas.android.com/apk/res/android"
            android:id="@+id/pager"
            android:layout_width="match_parent"
            android:layout_height="match_parent">
        </android.support.v4.view.ViewPager>
    </LinearLayout>  

    <LinearLayout
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:orientation="vertical" 
        android:layout_weight="3.75">
    <com.example.project.Multitouch
        android:id="@+id/fretBoard"  
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:background="#3EF20C"/>
    </LinearLayout>    
</LinearLayout>