I have what I been told is a 1924 32 Regulation Police revolver. SN is B394XXX What makes it different from the 1903 1905 and 1917 hand eject I frame revolvers besides the grips style? All the different guns from that model has gotten me a little bit confused.
First, welcome to the S&W Forum.
Your revolver does not look like a Regulation Police model to me. It looks like a .32 Hand Ejector Third Model that has had the front of the trigger guard removed. I could be mistaken and would only be sure if I could see the backstrap of the gun (behind the grip portion of the revolver). The stocks your gun is wearing are appropriate for a post-1920 revolver and a number of 394xxx for a .32 HE would put it in the early 1920s.
I'm not sure where you got those model designations, but there never were .32 caliber I frame guns that were referred to as Model 1905 or 1917 revolvers. The I frame .32 HE was called the Model of 1903 right up to 1917, when it became the .32 HE Third Model.
The Regulation Police was a different animal. It wasn't just the grip "style" that mattered. It was the design of the frame itself in the grip area. It had a unique stepped backstrap that necessitated a different pattern of stocks. The serial number was moved to the front strap of the grip frame, so it would not be hidden by the extension of the stocks that covered the bottom of the frame. If your serial number is on the bottom of the grip frame (butt of the gun), then it is definitely a .32 HE and not an RP.
I hope this clears some things up for you.
Jack
One more thing. I'm assuming you got the serial number you reported off the flat of the barrel (underside). The B at the beginning is not part of the serial number. It just designated that the gun shipped from the factory with a blued finish. It was stamped on the barrel flat but not on the rear face of the cylinder, nor on the grip frame.
OOPs! I just looked at your photo again and noticed the square butt stocks. This probably is an RP made in the '20s, because the .32 HE did not get a square butt (and the appropriate stocks for it) until after the war. Again, If we could have seen the backstrap, we'd have seen the step and the disappearance of the lower part of the backstrap under the stocks. In any case, the RP and .32 HE shared a serial number sequence, so the date will be the same - early 1920s.