I think a lot of us appreciate rimfire variants of our favorite guns. The HK MP5, the Walther PPQ, the SIG P322, and the GLOCK 44, among others, give us a cheaper way to fire a gun and train with something that’s similar to guns that are a bit bigger and more expensive.
This is hardly new. Colt may have done it first back in 1959 with the Colt Fourth Model Derringer. Colt’s first cartridge guns were the Thuer-designed second and third-model derringers chambered in .41 Rimfire, but production stopped in 1912 for these guns.