Remove your Powerbelt cups -- put them back in -- twst & turn them before you load em'. Your flyer may have been a bullet with the cup still attached or one that released the cup too late. If any of the cups feel too stiff going back in, spread a little of that gosh-awful bore butter around the edges of the cup.
Also, make sure your are seating the bullet exactly the same every time. Look for trends with flyers. Did it happen right after I swabbed (or) was the bore too dirty (or) maybe the action was closed & the old red disc was still present on the breechplug when you loaded more powder & a bullet (or) did you forget to dry-swab the barrel before it happened... etc.. etc.
