2D Raycast not colliding, but only some of the time...

So you can see my problem here:

https://www.youtube.com/watch?v=5K-0ES8EG4g

the laser sights will occasional clip clean through the walls, or stop short randomly. Other times they work as intended. I can't really work out what's causing this.

Here is my code.

 using UnityEngine;
 using System.Collections;
 
 public class LaserSight : MonoBehaviour {
 
     private LineRenderer Lren;
     public void Start () {
         Lren = GetComponent<LineRenderer>();
     }
 
     public void FixedUpdate() {
         if (Lren.enabled) {
             int layerMask = (1 << LayerMask.NameToLayer("Wall")) | (1 << LayerMask.NameToLayer("Enemies"));
             RaycastHit2D hit = Physics2D.Raycast( transform.position, transform.right , 100, layerMask);
             Debug.DrawRay (transform.position, transform.right);
             if (hit) {
                 Lren.SetPosition(1, new Vector3 (transform.InverseTransformPoint(hit.transform.position).x, 0,0));
                 //Lren.SetPosition(1, new Vector3( hit.distance, 0 , 0));
             } else {
                 //Lren.SetPosition(1, new Vector3( 100, 0 , 0));
             }
         }
         
     }
 }