Mesh Collider Troubles (Collision Detection)

Ok, so I've found a bunch of stuff regarding mesh colliders, but haven't been able to find anything regarding MY problem. The mesh collider is working, just not how I expected it to.

The problem is when I shoot my turret at the object with a mesh collider on it, it's stopping the "bullets" rather than destroying them, however when I shoot at a cube, it works properly and the bullet gets destroyed when it collides with it. There is probably something simple I'm missing, but I haven't been able to figure out what. Below I have posted an image and my code. If someone could give me a hint as to what's wrong with the mesh collider that'd be great.

Image:


Code:

Code (csharp):

1. void OnCollisionEnter(Collision collision)
2.     {
3.         //TODO: Implement Contact Explosion Effect
4.         //ContactPoint contact = collision.contacts[0];
5.         //Quaternion rot = Quaternion.FromToRotation(Vector3.up, contact.normal);
6.         //Vector3 pos = contact.point;
7.  
8.         Destroy(bullet);
9.     }

It's literally straight from the documentation minus the explosion , haven't gotten around to making the bullet hit effect yet. I don't think the error is in the code though, seeing as it's working properly with the cube. Sorry I'm kinda new to doing things with bullets and guns in unity I appreciate any and all help.