Trying to get TF2 style medic gun particles to flow down a bezier...goes a bit funky

LaserLine.cs

using UnityEngine;
using System.Collections;

public class LaserLine : MonoBehaviour {
  
	float timer; 
	public float duration = 5.0f; 
	
	public Transform P1;
	public Transform P2;
	public Transform P3;
	
	public GameObject particle; 
	ParticleSystem particleSystem; 
	int count; 
	 
	void Start () {  
		
		particleSystem = particle.GetComponent<ParticleSystem>(); 
	 
	}
	
	void ResetTimer(){
		timer = Time.timeSinceLevelLoad + 1.0f;  	
	} 
	
	public Vector3 GetBezierPoint(Vector3 P1, Vector3 P2, Vector3 P3, float t){
		return (P1*(1-t)*(1-t)+ 2*P2*(t)*(1-t) + P3*t*t);
	}
	
	void LateUpdate () {
 
		ParticleSystem.Particle[] p = new ParticleSystem.Particle[particleSystem.particleCount+1];
		int l = particleSystem.GetParticles(p);
		
		int i = 0;
		while (i < l) {
			p[i].velocity = GetBezierPoint(P3.position, P2.position, P1.position, Mathf.Lerp (0,1, p[i].lifetime / p[i].startLifetime));  //new Vector3(0, p[i].lifetime / p[i].startLifetime * 10F, 0);
			i++;
		}
		
		particleSystem.SetParticles(p, l);    
 
    } 
}