Problems With Weapon Sway

Hey, I've got this code for my current weapon sway system:

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 
 public class WeaponSway : MonoBehaviour
 {
     // Variables
     Vector3 vLastFacing;
     float flMaxViewModelLag = 1.5f;
 
     //-----------------------------------------------------------------------------
     // Purpose: Use this for initialization
     //-----------------------------------------------------------------------------
     void Start ()
     {
 
     }
 
     //-----------------------------------------------------------------------------
     // Update is called once per frame
     // Purpose: Calculates the sway the weapon has when looking around
     //-----------------------------------------------------------------------------
     Vector3 origin;
     Quaternion angles;
     Quaternion original_angles;
 
     void Update ()
     {
         Vector3 vOriginalOrigin = origin;
         Quaternion vOriginalAngles = angles;
 
         // Calculate our drift
         Vector3 forward = new Vector3();
         VectorExtensionMethods.AngleVectors(angles, forward, Vector3.zero, Vector3.zero);
 
         if (Time.deltaTime != 0.0f)
         {
             Vector3 vDifference = new Vector3();
             VectorExtensionMethods.VectorSubtract(forward, vLastFacing, vDifference);
 
             float flSpeed = 5.0f;
 
             // If we start to lag too far behind, we'll increase the "catch up" speed.
             // Solves the problem with fast cl_yawspeed, m_yaw or joysticks rotating quickly.
             // The old code would slam m_vecLastFacing with origin causing the viewmodel to pop to a new position
             float flDiff = vDifference.magnitude;
             if ((flDiff > flMaxViewModelLag) && (flMaxViewModelLag > 0.0f))
             {
                 float flScale = flDiff / flMaxViewModelLag;
                 flSpeed *= flScale;
             }
 
             // FIXME:  Needs to be predictable?
             VectorExtensionMethods.VectorMA(vLastFacing, flSpeed * Time.deltaTime, vDifference, vLastFacing);
 
             // Make sure it doesn't grow out of control!!!
             Vector3.Normalize(vLastFacing);
             VectorExtensionMethods.VectorMA(origin, 5.0f, vDifference * -1.0f, origin);
 
             Debug.Assert(vLastFacing.IsValid());
         }
 
         Vector3 right = new Vector3();
         Vector3 up = new Vector3();
         VectorExtensionMethods.AngleVectors(original_angles, forward, right, up);
 
         // Mouse X/Y
         float factorX = -Input.GetAxis("Mouse X");
         float factorY = -Input.GetAxis("Mouse Y");
         if (factorX > 180.0f)
         {
             factorX -= 360.0f;
         }
         else if (factorY < -180.0f)
         {
             factorY += 360.0f;
         }
 
         // If viewmodel lag equals 0 return to original origin/angles
         if (flMaxViewModelLag == 0.0f)
         {
             origin = vOriginalOrigin;
             angles = vOriginalAngles;
         }
 
         //FIXME: These are the old settings that caused too many exposed polys on some models
         // X
         VectorExtensionMethods.VectorMA(origin, -factorX * 0.035f, forward, origin);
         VectorExtensionMethods.VectorMA(origin, -factorX * 0.03f, right, origin);
         VectorExtensionMethods.VectorMA(origin, -factorX * 0.02f, up, origin);
 
         // Y
         VectorExtensionMethods.VectorMA(origin, -factorY * 0.035f, forward, origin);
         VectorExtensionMethods.VectorMA(origin, -factorY * 0.03f, right, origin);
         VectorExtensionMethods.VectorMA(origin, -factorY * 0.02f, up, origin);
     }
 }

Now what I'm unsure about is how to make it actually work in-game. My previous system had this to get it working:

 Vector final = new Vector (def.x + factorX, def.y + factorY, def.z);
 transform.localPosition = Vector.Lerp (transform.localPosition, final, Time.deltaTime = _smooth);

But I don't know how to do this for my current system.