Well, based on the responses, I got out my measuring stick and my collection of dovetails. And that's exactly right. One end of the dovetail is a bit smaller than the other on the buckhorn that I had taken off my cowboy and the Lyman 17A front sight. And I measured a dovetail blank that I had just for the fun of it - as expected, no differences in it. Thank-you for being so gracious to take the time to answer my question.