I use a CP 717 to buck rivets about the size you would use. It uses a .498 Parker shank. Anything larger than that would be something you only use once and the rivet sets would be very expensive and it would be very clumsy. The CP 717 works very well to cut rivets and Huck bolts as well. All kinds of chisels are available with .498 shank. Our trailers are all aluminum and of course we use aluminum rivets. But I have bucked steel rivets that were red hot just for the reason you are looking for. You need to make sure the rivet set matches the head or it will distort the head. You probably would want button head rivets so you would want to get a rivet set for button head rivets. We get all of our rivets and Huck bolts from Byler Rivet, but I'm not sure if they carry steel rivets any more. Big Flats Rivet specialize in rivets for antiques, and of course they charge for having something that is hard to find. Red hot steel rivets actually buck easier than aluminum rivets, so the CP 717 would do just fine.
Someone recommended these guys to me. I have never bought anything from them, but it looks like their prices are much more down to earth. And you would probably want to buy rivets by the pound so you can practice setting them. It takes practice just like welding.
http://www.piehtoolco.com/contents/en-us/d1424.htmlYou might be able to use something like a 5x gun with a .401 Parker shank. You might give these guys a call. They will probably explain to you how to buck rivets. Most important is that you use a riveter, not a plain old air chisel. You need to have a very controllable throttle.
