Stuffed a dryer-burned Wiggy bag into a box and duct taped it closed. Tightly closed. I think it would have stopped a 45 round. My shafts with practice points went in about 2 or 3 inches at 20 yards.
Stuffed the same bag into a heavy-mil plastic bag and am still shooting it. Just fluff the bag as you would a pillow every once in a while.
So I had Wiggy send me up a box of scrap bulging at the seams. That will stop any broadhead after a few inches.
Just a thought...
Then get yourself a new sleeping bag! I know just the place!