If you searched the forums for "orange tip" or even "orange" you would find quite a few topics about removing it, just so you know for next time. But I'll tell you anyway:
If it's a plastic flash-hider, you will need a small allen wrench and a replacement flash-hider.
If it's a metal flash-hider, painted orange, then use non-acetone nail polish remover on a washcloth or something similar and scrub til it goes away.
Or you could always sand it off and bake a new coat on there, but that's a little more work.
This should answer most ramifications of this question, so there you have it and I hope it helps. If you need more info, search the forums or feel free to send me an e-mail.
Thanks,
Kamikaze_SM@hotmail.com