RAW HM1000X LRT .22 single shot tray

3d print one for free or modify a Marauder SST lift it up a little. You can Even make one out of a piece of throw away scrap piece of wood it's easy copy the lower part of the magazine slide it in. Basic hand tools work 

I'm sure Martin's tuning company the former RAW has SSTs for Rapids which is the same thing if you want to pay money for it..

Other Benjamin variant SSTs from Nova Freedom/Liberty/Seneca Aspen/Avenger/Gauntlet can work as well just glue a piece of wood or plastic to lift up or follow the lines to 3d print a copy a little taller.

Don’t worry about it. I bought one from RAW for my .25 and found it easier to load then straight into the chamber with my thumb.

try RAW If not look to SMW Engineering

CARM Magazines. They work like a Rowan.

I haven’t used this particular model, but I would also suggest CARM.