Greetings to you all! this is my first posting and hopefully not my last. I have been seriously considering both the Ruger SP101 and the Ruger GP100. I think I am leaning towards the GP100, however I am under the impression that this revolver will only fire .357's? Can someone please give some good advice as far as whether or not having a .357 only revolver is a wise choice or not. I realize this question probably needs more qualifiers than I am lending, however, I am more concerned with understanding how calibers and rounds work overall...ie. what goes with what, what can be fired and what cannot? I realize that these are very green questions but I am "unseasoned".