Yeah, I always found that interesting too. It formed the foundation of my wonderment of why all the extra barrel steel as compared to larger bores which obviously fueled the OP's query at the start of this thread and for which I have no answer, other than one of matching barrel chamber dimensions to a frame designed for larger barrels.

"You can lead a man to logic, but you cannot make him think." Joe Harz
"Always certain, often right." Keith McCafferty