I have a question about the physical problem between the player and the projectile.

Unity Engine
1

I’m creating a Unity 3D game and implementing a function where the player fires a gun.

When the player attacks with a gun, the bullet is fired forward through the Rigidbody velocity from the bullet launch position.
Bullets are fired well, but there is a problem that the character rotates every time it is fired.
(Rigidbody is applied to both player and bullets)
I think it’s a problem with Rigidbody, so can you tell me the cause and solution of this problem?

public class Weapon : MonoBehaviour
{
    public enum AttackType { Melee, Range };
    public AttackType type;

    public int damage;
    public float speed;
    public BoxCollider meleeArea;
    public TrailRenderer trailEffect;
    public Transform bulletPosition;
    public GameObject bullet;
    public Transform bulletCasePosition;
    public GameObject bulletCase;
    public int maxAmmo;
    public int currentAmmo;


    public void UseWeapon()
    {
       if (type == AttackType.Range && currentAmmo > 0)
        {
            currentAmmo--;
            StartCoroutine(Shot());
        }
    }

    IEnumerator Shot()
    {
        // fire bullet
        GameObject instantBullet = Instantiate(bullet, bulletPosition.position, bulletPosition.rotation);
        Rigidbody bulletRid = instantBullet.GetComponent<Rigidbody>();
        bulletRid.velocity = bulletPosition.forward * 50;
        yield return null;
      
        // bullet case
        GameObject instantBulletCase = Instantiate(bulletCase, bulletCasePosition.position, bulletCasePosition.rotation);
        Rigidbody bulletCaseRid = instantBulletCase.GetComponent<Rigidbody>();

        Vector3 caseVector =
            bulletCasePosition.forward * Random.Range(-3, -2) + bulletCasePosition.up * Random.Range(2, 3);
        bulletCaseRid.AddForce(caseVector, ForceMode.Impulse);
        bulletCaseRid.AddTorque(Vector3.up * 10, ForceMode.Impulse);
    }
}
2

I suspect the bullet spawns inside the player‘s collider, thus both are pushing themselves out of this collision. You‘ll need to go into Project Settings — Physics and set up collision mask, assign player to the player collision layer and bullets to a PlayerBullets layer, then make both not interact with each other. See physics collision mask/layer in the manual.