diff --git a/src/musrPrimaryGeneratorAction.cc b/src/musrPrimaryGeneratorAction.cc
index a144e6a..2baf7d9 100644
--- a/src/musrPrimaryGeneratorAction.cc
+++ b/src/musrPrimaryGeneratorAction.cc
@@ -271,8 +271,10 @@ void musrPrimaryGeneratorAction::GeneratePrimaries(G4Event* anEvent)
   G4double px, py, pz;
   px = p*sin(xangle);
   py = p*sin(yangle);
-  // works for beam along +-z only for now
-  pz = zDirection * std::sqrt(p*p - px*px - py*py);
+  pz = std::sqrt(p*p - px*px - py*py);
+
+
+  // Now rotate so that beam propagates along /gun/direction
 
   // Proper rotation of beam direction as follows:
   // hat{n} is beam direction unit vecrot and vec{p} is momentum vector
@@ -280,7 +282,25 @@ void musrPrimaryGeneratorAction::GeneratePrimaries(G4Event* anEvent)
   // where R is a rotation matrix around (hat{z} x hat{n}) - cross product
   // with an angle of acos(hat{z} dot hat{n}) - dot product
   // i.e. R is a rotation around (-n_y, n_x, 0) with angle acos(n_z). 
-  // G4RotationMatrix* R = new G4RotationMatrix(G4ThreeVector(-nx,ny,0),acos(nz)*deg);
+
+  if (xDirection == 0 & yDirection == 0) {
+    // Rotation does not work for beam direction along z.
+    pz = zDirection * pz;
+    // No change to the beam spot...
+  } else {
+    G4ThreeVector* PVec = new G4ThreeVector(px,py,pz);
+    PVec->rotate(std::acos(zDirection),G4ThreeVector(-yDirection,xDirection,0));
+    px = PVec->x();
+    py = PVec->y();
+    pz = PVec->z();
+
+    // Rotate also beam spot
+    G4ThreeVector* RVec = new G4ThreeVector(x-x0,y-y0,z-z0);
+    RVec->rotate(std::acos(zDirection),G4ThreeVector(-yDirection,xDirection,0));
+    x = x0+RVec->x();
+    y = y0+RVec->y();
+    z = z0+RVec->z();
+  }
 
   // Assign spin 
   G4double xpolaris=0, ypolaris=0, zpolaris=0;