OK, I took the challenge and made an arrow shooting slingshot. I like lead and steel balls, but I realize that an arrow with a broad head can cause more damage. Those who want to hunt larger animals may have more success with arrows. So, here is my idea about how to shoot arrows from a slingshot.
Of course I had watched the "Hunt big game with a slingshot" video series on youtube, and I think the "whisker buscuit" idea is valuable. But I did not want to spend 20 to 50 Euros just on the biscuit!
So I had to solve a number of problems.
1. The draw length limitation
Arrows are rarely longer than 32", and such long arrows weigh more than a .75" (19mm) lead ball! An increase of the draw length beyond 32" is absolutely necessary to achieve serious speed.
So I added two metal tubes to the grip, moving the whisker biuscuit about ten inches towards the shooter. This way, you can draw out a 32" arrow 42" from the pouch.
2. The pouch problem
Gripping the rear end of an arrow though a leather pouch is much harder than gripping a thick lead ball. The "golf tee" solution proved negative for the balance of the arrow, so I had to solve the issue otherwise.
The solution: A change to the pouch! Close to the band attachment, one more hole was punched to either side of the pouch. Through these holes, rubber bands had been tied to both the upper and the lower rim of the pouch.
This allows you to hold the bunched up rubber just like a slingshot ball, and it automatically squeezes the arrow tightly in place. Problem solved.
3. Cheap whisker biscuit
A whisker biscuit is essentially just a brush that is formed like a ring, with the "whiskers" directing to the center of the ring. It guides the arrow, but it lets the stabilizers (feathers, rails, whatever) pass easily. Very nice!
So I decided to go with a whisker biscuit, which I made myself, from one dollar baby bottle brushes. I simply bended the brushes, cut off all excess and tied two of them together so they form a ring. This works, and is really cheap.
I have made video about the modification. Here it is: