That would be a good application for a universal charge bar. You could tweek the ingredients (downward) until everything just fits, then send it off to be chrono'd.
Here is what I am using for skeet and it works very well:
AA 28 (old style not HS)
Win 209/chedite is ok to sub
claybuster wad
5/8 oz lead shot.
You might need a touch of filler depending on your loader.


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