Actually, it's a very long story. One covering more than a century but I will try to condense it and still retain the essence.
Once upon a time, there was this puny little 38. Not the robust 38 special. No, no. Just a puny little 38. Puny was asked to do a lot of things. Some he was more than capable of. Others, not so much. Well, his great uncle asked what could be done about it. See, puny had replaced a rather big guy on the block. His name was 45 Long. Mr. Long had been around for a long time and done the many tasks well. But he was beginning to be a bit long in the tooth, (no pun intended). That's when 38 came into view.
Any way, after some testing, great uncle decided he was not happy with puny or any of his friends and he longed for the days of 45 Long. This fellow called John said, No problem uncle. I have a project I'm working on that might be what you desire. The end result of that conversation was another big fellow named 45 Auto. Now Auto reigned supreme for a while but puny and his friends were not very forgiving. Every 15 years or so they would gather and attempt to knock Mr. Auto off his podium. Not by going bigger, but by going faster. It was the tortoise and hare syndrome all over. Anyway, every now and again, one of the puny fellows would get a bit of notoriety and claim a piece of the action. Never did they replace Mr. Auto. BUT they were always able to hide inside him when the real SHTF. And now you know the answer to your query!!
