9mm revolvers

[whm1974]

Because CA has a patent on their extractor design.
So there's that,

Since Colt, S&W, and Ruger(for .ex) are much larger companies with more resources, they couldn't come up with their own design? Wasn't there an earlier revolver called the Medusa that did the same thing, but with multiple 9mm and .38 cartridges with .355" to .358" caliber bullets?

The Medusa Model 47, only a few hundred even exist...
https://en.wikipedia.org/wiki/Medusa_Model_47

 

[whm1974]

Well the Medusa can also shoot smaller .32 and .30 calibers such the .32 ACP and The Soviet Union's .30 TT. As expeted, the firearm does have a few issues, such as lower accuracy with shorter cartridges and the main part(s) that make this revolver even work at with such a wide range of ammo, is fairly fragile that breaks if forcing stuck empty cases out.

In other words, not very practical to own and use.