Well, I have a model 10-2 and a model 19 cylinder fit in it fine once I trimmed the barrel extension (only difference between a 19 cylinder and a 10 cylinder is about 0.1 in length). I also had to trim the frame lug a bit because it was a recessed cylinder. Wouldn't have to do that on a non-recessed cylinder like a on a model of course. So a model 10 frame with a model 13 barrel screwed into it should have no problems with a K frame 357 cylinder fitting in the window, I later installed a used short model 19 barrel in the frame and the gap came right at .005 Works fine.