Brent: All of us who reload for the 16ga are forced to tinker to a certain degree. Cutting styrofoam disks to use as filler--even when wads like the DR-16 are available when working up 7/8 oz reloads in 2 3/4" hulls--is one solution, but somewhat time consuming. When the reload leaves too much space for a good crimp, I usually compensate by dropping in a Cheerio or 2 on top of the shot. Takes up space without adding much additional weight. Crimps are pretty good and the filler doesn't seem to hurt the performance of the reload. I find that I need something--usually just one Cheerio-- to get better crimps with the current black Herters hulls and DR-16 wads.
