They have no skirt, they are a flat-based bullet design.... It is curious, as they work normally in a LW barrel.... The bolt seal in these guns doesn't leak.... The only other thing that is different is the pressure, which in this gun is 1800 psi and in my Disco is much higher.... hmmmmmmmmmmm.... maybe that is the answer, not enough pressure to overcome the extra drag of the multiple driving bands.... Yeah, thinking on it, that's probably the culprit....
EDIT: Nope, it's not the pressure.... I checked my notes and achieved 75 FPE at 1600 psi while testing the Mr. HollowPoints in my Disco.... Weird !!!
Bob