If a Cowboy Action Mounted Shooter was loading groundup walnut hulls in his blanks, he or she would be disqualified at any sanctioned shoot. What brakes the baloons is the still burning grains of BP that shoot out about 10feet.
At all the shoots I have read about, the guns are loaded all from the same furnished boxs of blanks.
At least, that is the way it has been explained to me by several mounted shooters.
You could ask on the SASS Mounted Shooters forem if realy interested. I have seen several threads on loading BP blanks listed on the SASS wire in the last few weeks, however I didn't read them. I had no intrest in loading blanks. But then, I never thought of using them for BEE's!!!!!
Greeenriver(SASS #38681)