Bob you are correct. I have not seen Colt New Police rounds for sale anywhere. I have an old NP revolver made by Colt I inherited from my grampa. It is the same brass dimensions as the .38 S&W with a flat point bullet. Grampa used to use nipper pliers to cut a bit off the end of the bullet so it would chamber in the Colt. The end of the bullets would stick out of the cylinder making it impossible to close.
Note the .38 S&W/.38 Colt New Police is larger in diameter than the .38 Special/.357 Mag and will not fit into the chamber of one.
No matter how many times you do it and nothing happens it only takes something going wrong one time to kill you.