To go with my full-size Kimber .45 cal., 1911 pistol, I bought a Kimber .22 rimfire conversion, which includes a replacement slide, barrel, recoil spring, magazine, etc., for $300. I fired it at the range today.
I had read that the conversion was fussy with ammo - and sure enough, it didn't like Federal at all. Remington Golden Bullet ammo performed much better. I think the Ferderal's trouble could have been caused by wax-coated bullets and/or insufficient power. I've read that CCI ammo is recommended for use with the conversion, and I will use that next time.
I loaded five rounds of the Federal in a magazine: one round cycled properly, two failures-to-eject, and two failures-to-load. I then shot about 50 rounds of the Remington Golden Bullet, and had one failure-to-eject, but the rest cycled properly. Each of the failures-to-eject involved the empty casing sticking in the chamber, requiring a pocket knife to pry it loose.
The gun has worked perfectly using .45 FMJ ammo and the original slide, etc.
The .22 conversion is fun and cheap to shoot, and a 1911 feels good in my hand.
But for $300, you could buy a stand-alone .22 pistol