When looking at the options available for Caspian frames, I see that there are a few options for the beavertail. Standard GI, Caspian/Wilson style, and .250 Radius. What are the differences? I plan on purchasing a Jem frame, and I noticed on their site they say they can get a better safety match to frame with their safety. I imagine that the difference in choices between these has something to do with frame fit? Enlighten me please! Thanks!