They already made the six shot fixed sight 9 mm K frame Model 547 with 3" and 4" barrels. It had six spring loaded tabs in a beryllium copper extractor. Loading cartridges depressed the tabs which then snapped back out into the extractor grooves. They did not have clearance between the cylinder and recoil shield for moon clips. Charter Arms uses a similar system today in 9 mm, .40S&W and .45 ACP snub noses. To prevent cushioning the firing pin blow which would result in missfires the Model 547 also had a spring loaded plunger that protruded from the recoil shield to fully seat cartridges.
Model 547s were not perfect. The extractor grooves in some brands of cases worked well but other brands or lots did not. HKS made speed loaders but the cartrdiges would only drop part way in. They still had to be individually pressed in past the spring loaded tabs. Model 547s were troublesome and did not sell well in the USA. French police bought them. They might have been designed specifically for them.
Since the Model 547 was discontinued S&W has made Model 940 enclosed hammer J frames and are currently making 7shot L and 8 shot N frame 9 mm revolvers.
The revolvers that are the closest to moon clip loading K frames are Ruger's fixed sighted 9 mm Service Six and Speed Six. They were made blued and stainless and with 3" and 4" barrels.
Before Obama was elected I could buy 1,000 Wolff 9 mm FMJ cartridges for $84 out the door. I wanted a six shot double action to shoot them in matches. What I learned is that double action revolver extractors are not strong enough to extract five or six steel .40S&W or 9 mm cases at once. You have to use an automatic pistol, a single action revolver or go back to more expensive brass cases.