I believe there are a couple, and I've seen one before that looked like it was rifle rated. It was fairly thick steel, with a thick Lexan window on it. It would have worked against 5.56 and 7.52 bullets, but I don't know about anything bigger and more powerful than that. If you want to find one, look on http://www.botachtactical.com/botach/index.html they have a ton of cool stuff on there.
Protech sells Level III and IV shields. Depending on size and threat level, these shields can weigh a lot. Level III 16"x32" weighs 32 lbs. Level III 26"x48" is 71 lbs. Level IV 24"x48" is 157 lbs. The heavy shields use wheels.