In the days when we used dump pouches, I don't think that much thought was given to tactical reloads and such.
Adam-12 accurately portrayed how LAPD set up their Sam Browne belts. A right hander had the holster on the right, and starting at the buckle as 12 o'clock and going counter-clockwise from the wearer's perspective, the dump pouches were first, then the night stick ring, then the key ring, then the handcuff pouch.
Our state patrol here in Missouri used the same set up.
That said, at some point, some agencies got wise to the need to have the loose ammo convenient to the dominant hand for dexterity.
Therefore, NYPD changed at some point to the dump pouch in front of the holster on the stong side (between the holster and the buckle of the belt), which makes the most sense.
This allows the shooter to transfer the revolver to the weak hand as the cylinder is swung out, then the weak hand turns the revolver up and ejects the spent cases while the strong hand unsnaps the dump pouch letting the spare rounds fall into the strong hand (usually). Then that strong hand, which is the hand with dexterity, fumbles the six cartridges and often gets them all in the charge holes without dropping any. LOL
I think sigp220.45 has it right. The spare shells ought to be on the right side in front of the holster (assuming you are a right hander).
I believe sigp220.45 is retired from the Bureau and I am certain he remembers the Bucheimer holster and the 2x2x2 ammo carrier for the Model 13s with 3 inch barrels, which agents (at least the ones I knew) carried in front of the holster on the right side.
Later, Bucheimer made a version that actually had the 2x2x2 attached to the holster to make sure folks carried the spare ammo rather than leaving the 2x2x2 in the desk drawer.
As an aside, Gene Desantis still makes a holster similar to the old Bucheimer with 2x2x2 carrier attached, but only for the J frame, not the K frame.
Long answer for a simple question. Sorry.
