I think I've seen pics of someone doing that on the interwebs somewhere.
I tried so hard to find a pic. Even stumbled across a FN FAL forum, and started reading about a few people using that same tape for the hand guard to protect from heat.
I don't have any on my guns, but I bought some of that tape for the intake on my car, and it seemed to help significantly. Intake air temps are cooler, which lets me use low test fuel in the summer, without pinging or detonation.
If I had a rifle that needed it, I'd probably have it on that rifle too.