OnTriggerEnter doesn't work

ok Bullet tip is Character controller (Small size) as it cannot be X size large but only global Y size that's why it's 1, 1, 1 scale The tail follows the tip and scales acordinantly I checked Tail is 2 frames inside bodies and nothing is reported.

75% of the time Tail Does trigger the Body but it doesn't work every time.

any Idea why?

The Bullet that passes through 2 bodies

here's the BodyRecognizing bullet script:

 using UnityEngine;
 using System.Collections;
 
 public class BodyPartHitDetection : MonoBehaviour {
     public float BodyVulnerability = 1;
     public Stats StatsScript;
     private Spawner SpawnerScript;
     private ProjectileStats PrStatsScript;
     
     
     static int Debugint = 0;
     void Start(){
         SpawnerScript = GameObject.FindGameObjectWithTag("Spawner").GetComponent("Spawner") as Spawner;
     }
     
     void OnTriggerEnter(Collider Other){
         if (Other.tag == "Projectile"){
             Debugint ++;
             // get component from the parent
             if (Other.name != "Tail"){    PrStatsScript = Other.GetComponent<ProjectileStats>();                    Debug.Log(Debugint + "Tail");}
             else {                        PrStatsScript = Other.transform.parent.GetComponent<ProjectileStats>();    Debug.Log(Debugint + "Head");}
             // so we don't hit our self
             if (PrStatsScript.IgnoreObject != gameObject){
                 Debug.Log(Debugint + " " + StatsScript.name + " Was Hit On The " + transform.name + " with damage: " + PrStatsScript.Speed*PrStatsScript.Weight*BodyVulnerability);
                 // we remove some health
                 StatsScript.Health -= PrStatsScript.Speed * PrStatsScript.Weight * BodyVulnerability;
                 // we Deactivate the bullet so it won't hurt us any longer
                 SpawnerScript.DeactivateMeF(Other.gameObject);
             }
         }
     }
 }

here's the Bullet Tip && tail Script:

 using UnityEngine;
 using System.Collections;
 
 public class ProjectileStats : MonoBehaviour {
     // all 3 needed when land on enemy so he knows how to calculate the damage
     public Transform Tail;
     public GameObject IgnoreObject;
     public float TimeFiered = 0;
     public float Speed = 0;
     public float Weight = 0.1f;
     
     private Vector3 Pos = Vector3.zero;
     private MathFunctions MF;
     private Spawner SpawnerScript;
     
     // Tail
     private Vector3 LastProjectileTipPosition = Vector3.zero;
     private Vector3 BeforeLastPosition = Vector3.zero;
     
     private int FRQ = 0;
     void OnEnable(){
         FRQ = 0;
     }
     public void Setup(float CurrentTime, float ProjectileWeight, float TopProjectileSpeed, Transform FieredFrom , GameObject ObjectToIgnore, Spawner _SpawnerScript){
         FRQ = 0;
         SpawnerScript = _SpawnerScript;
         TimeFiered = CurrentTime;
         Weight = ProjectileWeight;
         
         LastProjectileTipPosition = FieredFrom.position;
         BeforeLastPosition = FieredFrom.position;
         UpdateTailPositionF();
         IgnoreObject = ObjectToIgnore;
     }
     public void UpdateTailPositionF (){
 ScaleAndPositionFromTo(LastProjectileTipPosition, transform.position, Tail);
         MF.V3ScaleF (BeforeLastPosition, transform.position, Tail, 95f, 0.1f);
         
         BeforeLastPosition = LastProjectileTipPosition;
         LastProjectileTipPosition = transform.position;
     }
     void ScaleAndPositionFromTo(Vector3 From, Vector3 To, Transform ScaleMe){
         float temp = MF.V3DistanceF(From, To);
         Vector3 v3t = MF.V3DirectionF(From, To);
         ScaleMe.position = From + (v3t * (temp/2) );
         ScaleMe.localScale = new Vector3(1, temp*10, 0);
     }
     void Update(){
         // we calculate speed once per 20 frames
         if (FRQ == 0){
             Pos = transform.position;
         }
         else if (FRQ == 1){
             Speed = MF.V3SpeedPerSecF(Pos, transform.position, Time.deltaTime);
             // we delete the bullet so it won't flow through the space endlessly
             if (TimeFiered + 20 < Time.time){
                 SpawnerScript.DeactivateMeF(gameObject);
             }
 //            Debug.Log(Speed);
         }
         // let's check again
         else if (FRQ == 20){
             FRQ = -1;
         }
         FRQ ++;
     }
 }

and some MathFunctions I've got:

 using UnityEngine;
 using System.Collections;
 
 public struct MathFunctions {
     // always positive
     public float PositiveF (float FloatToChange){
         if (FloatToChange < 0){
             return (FloatToChange * (-1) );
         }
         return FloatToChange;
     }
     // always negative
     public float NegativeF (float FloatToChange){
         return PositiveF(FloatToChange) * -1;
     }
     // V3 Distance
     public float V3DistanceF (Vector3 From, Vector3 To){
         float TempX = From.x - To.x; TempX *= TempX;
         float TempY = From.y - To.y; TempY *= TempY;
         float TempZ = From.z - To.z; TempZ *= TempZ;
         return Mathf.Sqrt(TempX + TempY + TempZ);
     }
     // Direction
     public Vector3 V3DirectionF (Vector3 From, Vector3 To){
         return (To - From).normalized;
     }
     // Distance / sec
     public float V3SpeedPerSecF (Vector3 From, Vector3 To, float InTime){
         return (V3DistanceF(From, To) ) / InTime;
     }
     // V3 Point
     public Vector3 V3DirectionDistancePointF (Vector3 From, Vector3 To, float Length){
         return (From + (To.normalized * Length) );
     }
     // V3 Scale
     public void V3ScaleF (Vector3 From, Vector3 To, Transform ScaleMe/*, Vector3 WitchAxis*/, float PercentScale, float LocalScaleSize){
         float TempDistance = V3DistanceF(From, To);
         ScaleMe.position = From + (V3DirectionF(From, To) * (TempDistance/2) );
         From = ScaleMe.localScale;
 //        if (WitchAxis.x > 0){From.x = 10 * TempDistance * PercentScale;}
 //        if (WitchAxis.y > 0){From.y = 10 * TempDistance * PercentScale;}
 //        if (WitchAxis.z > 0){From.z = 10 * TempDistance * PercentScale;}
         From.y = ( (TempDistance / LocalScaleSize) / 100 ) * PercentScale;
         ScaleMe.localScale = From;
         ScaleMe.LookAt(To);
     }
     // V2 Angle
     public float V2AngleF (Vector2 From, Vector2 To){
         
 //        float DotProduct = From.x * To.x + From.y * To.y;
 //        float MagnA = From.x * From.x + From.y * From.y;
 //        float MagnB = To.x * To.x + To.y * To.y;
 //        MagnA = Mathf.Sqrt(MagnA);
 //        MagnB = Mathf.Sqrt(MagnB);
         
         
         Vector3 Cross = Vector3.Cross(From, To);
         
         float ang = Vector2.Angle(From, To);//Mathf.Acos( (DotProduct / (MagnA*MagnB) )  ) * Mathf.Rad2Deg;
         if (Cross.z > 0){
             ang = 360 - ang;
         }
         return ang;
     }
 }
 

what bugges me the most is bullet tail is 2 frames inside the body as it's 2 times longer than 1 frame distance

and if speed is slow enough like 50m(points)/s it always works mostly with the head tip

OH and the Body Trigger Collider s: