Here are photos of chamber casts of the original H&R .357 mag chamber below the cast of that chamber reamed to .357 maximum. As you see, the max reamer removed very little metal, never even reached the throat, and one cannot load out to the lands even with the .357 maximum. And yes, you can use .367 magnum dies even for the .357 Maximum, in fact I know of no manufacturer who even makes a set of dedicated dies for the maximum. although many people do seem to get fine accuracy from their .357s, my rifle is not among them. I've tried a great variety of loads and some of the "accuracy tips" and best loads on best day will do no better than 3 MOA, if even that well.