Help with Space Shooter tutorial bolt movement.

My apologies if this has already been answered. I found solutions on the forum what I believe to be similar problems, but every fix I’ve tried hasn’t resolved the issue. My issue is with the movement of the bolt VFX.

Here’s the code;

using UnityEngine;
using System.Collections;

public class Mover : MonoBehaviour {

private Rigidbody rb;
public float speed;

void Start ()
{
rb = GetComponent ();
rb.velocity = transform.forward * speed;
}

}

The movement of the bolt doesn’t seem to be continuous, it jumps the value of the speed up. I tried the interpolate setting on the rigid body, but then the bolt basically flickers the range of the speed and the moves up.

If you need more, please let me know, I can upload a video.

This is the link to the tutorial.

sorry, I don’t quite get the issue. Does the bolt move up once then stop or does it keep moving up the screen but in steps rather than a continuous movement?