Howdy
One of my favorite subjects.
It is a little bit difficult to compare the Model 10 and the Police Positive (or Police Positive Special as the 38 Special version is called) because they are on different frame sizes. The Colt is built on the same frame as the Detective Special, and it is slightly smaller than the Smith K frame. The next larger frame size for Colt is the one the Officer's Model is built on and it is noticeably more massive than a K frame.
If you ask me, and you did, the K frame is the perfect size for a 38 Special revolver. It's all in the cylinders. When Smith developed both the K frame and the 38 Special cartridge to go along with it in 1899, they came up with the perfect combination of size and weight, at least in this shooter's humble opinion. They did it again in 1908 when they built the New Century model, popularly called the Triple Lock and the 44 Special cartridge to go along with it. The perfect size for a 44 or 45 caliber revolver. Handle a Colt Model 1917 sometime. It is a much larger and I think a more awkward gun than the Smith version.
Don't get me wrong, I enjoy shooting a Police Positive as much as the next guy, but I just think the K frame is the ideal size for a 38. That's partially why I collect Smiths, and not Colts.
Ergonomically, I feel the Smith is a superior design. Pushing the thumb latch forward on a Smith is the simplest way to open a cylinder. Easily done with one hand as long as one does not slam the cylinder open. For me, it always requires two hands to open up a Colt, I have to hold the gun with two hands in order to hook my thumb over the release and pull it back. Not as shooter friendly a design as the Smith.
Another feature that makes the Smith a better design is the spring loaded latch at the front of the ejector rod. I feel this makes for a more secure lock up, with the cylinder prevented from hinging open from both the front and the back. This feature has been standard on every S&W swing out cylinder revolver with the exception of the Model 1899, which was only made from 1899 until 1903, like this one.
After that, S&W always put a latch at the front of the ejector rod, whether it was a shrouded one like this:
Or an unshrouded one like this:
Colts on the other hand, usually only secure the cylinder at the rear.
Then of course there was the Triple Lock, but that's another story for another time.
I don't do all that much work on the inside of Smiths, they usually don't need it. But from the Gunsmith's point of view I believe the nice, simple straight S&W mainspring is a lot simpler to thin down than the Colt's V shaped design.
Now, in all fairness, as a collector and shooter mostly of older Smiths, I do have to admit that the hammer design of the older guns left something to be desired. It's pretty easy for the thumb to slip off the hammer spur when firing single action with the older design, particularly on a hot, sweaty day. The knurling was not very pronounced, and the hollow in front of the knurling was shallow enough that the thumb could easily slip off when cocking the hammer.
In the late 1940s there were some transitional hammer designs that addressed this issue, such as the hammer on the K-38 at the top of this photo.
But once the short throw hammer was developed, with its new profile and deep knurling, the problem of slippery thumbs went away with Smiths.
So there you have it from an extremely biased shooter and collector why I like DA Smiths over DA Colts.