Some hybrids. Most are fine. The problem is that the center post of the atty, when it protrudes (like the one in the pictures above) past the threaded part, can cause a short in the REO, causing the spring to collapse. A good rule of thumb is to visually inspect any new atty or carto before you screw it on the first time. If the center post sticks out past the bottom of the atty, you can try to mash it in on a tabletop, or use a screwdriver on it if it has the groove for it, but your best bet is to save it for some other, less important mod.
