Comparing various lots, many folks believe that RL-19 and RL-22 can change positions, or test out as essentially identical. Other lots have them in their intended positions, with RL-19 a bit faster than RL-22.
Back when they were still Hercules, they dropped RL-12 because it could test out close to RL-15. They eventually brought out RL-10X to bridge the large gap between RL-7 and RL-15.
Now that they've brought out RL-17, it would not be unreasonable for them to now drop 19 - if in fact they plan to trim the product line at all.
