Shooter.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class Shooter : MonoBehaviour {

    public GameObject shotPrefab;
    public float shotVelocity = 20.0f;

    void Start () {

    }

    void Update () {
        if (Input.GetMouseButtonDown (0))
        {
            GameObject shot = GameObject.Instantiate(shotPrefab, transform.position, transform.rotation) as GameObject;
            shot.GetComponent<Rigidbody>().velocity = transform.forward * shotVelocity;
        }
    }
}