TNRAT: In reading the thread I see not only you, but several others are a little confused.
First, the remington .22 jet is a necked down .357 to .22 caliber. NOT in no way the same as the .22 WMRF. It is a center fire cartrige. The hammer was convertable to shoot either centerfire or rimfire to shoot .22 lr.
The gun came with the inserts so you can stick .22lr in them, and in turn insert them in the chambers. Kind of a slow tedious task. Some of the guns came at extra price with two clyinders, a better idea. I seldom wear ear protection, but on these you need them. Here is my model 53. Shown with stag, but I have the originals. I dont have the extra clyinder in .22lr. Wish I did!