Unless you control this behaviour directly at the webserver, you're leaving it up to the user's browser to decide whether they want to observe the redirect or not.
Personally, my web host offers a good menu selection options screen where i can set this behaviour at the web server level. (In case you're wondering, it just adds/changes a line to a config file in a specific directory on the server). If however you have direct access to the web server then you may want to read up on how to configure it. Search online and you should find some great tutorials, FAQ's, walkthroughs, etc. You'll find this a much more powerful way to do things so i hope you do have this option open to you.
Welcome to tilted programming
