Mesh Deformation

I'm attempting to create a mesh deformation script. My approach to this is to access each vertice in an object and then move it a certain amount based off its distance from the colliding object and the direction its being hit from. This is what I tried (the script is on the projectile that is supposed to be deforming the mesh that its hitting):

 void OnCollisionEnter (Collision collision) {
 
         Mesh mesh = collision.transform.GetComponent<MeshFilter>().mesh;
         Vector3[] vertices = mesh.vertices;
 
         int i = 0;
         while (i < vertices.Length) {
             float distance = Vector3.Distance(vertices[i], collision.transform.position);
             if(distance > hitRadius) return;
             float vertMove = distance/hitRadius;
             Vector3 localDirection = transform.position - collision.transform.position;
             vertices[i] += (localDirection * vertMove);
             i++;
         }
         mesh.vertices = vertices;
            mesh.RecalculateBounds();
     }

The problem is that it doesn't do anything until the hitRadius is larger than the object, and then on collision, it moves the whole object. What am I doing wrong here?

EDIT

Okay so after doing some research on the forums, BigMisterB wrote this script (corrected by me):

 using UnityEngine;
 using System.Collections;
 
 public class MeshDeform : MonoBehaviour {
 
     public Vector3 relativeVelocity;
 
     void Update () {
 
         transform.Translate(relativeVelocity * Time.deltaTime);
     }
 
     void OnCollisionEnter (Collision collision) {
 
         MeshFilter mf = collision.collider.GetComponent<MeshFilter>();
         Mesh mesh = mf.mesh;
 
         Vector3[] vertices = mesh.vertices;
         Vector3 hitPoint = transform.InverseTransformPoint(collision.contacts[0].point);
         float hitRadius = relativeVelocity.magnitude;
         Vector3 hitDir = transform.InverseTransformDirection(-collision.contacts[0].normal);
 
         int i = 0;
         while (i < vertices.Length) {
             float distance = Vector3.Distance(vertices[i], hitPoint);
             Vector3 dir = (vertices[i] - hitPoint);
             if(dir.magnitude < hitRadius){
                 float amount = 1 - dir.magnitude / hitRadius;
                 Vector3 vertMove = hitDir * amount;
                 vertices[i] += vertMove;
             }
             i++;
         }
 
         mesh.vertices = vertices;
         mesh.RecalculateBounds();
     }
 }

So the script works now, but unfortunately the wrong vertices are being affected. For some reason, when I hit the object, the vertices completely opposite of the vertices that are hit are affected. Any ideas why that happens?