Say what you will fellows, but sand is what we used long ago. All these expensive broadhead targets haven't been in production forever, you know.
Brian, if you got the itch just give it a shot. If you have a back yard just puilt you a 3 sided box out of flakeboard and a couple 2x4's. Sand will cause some wear on the heads, mostly just removing the anodizing and will definitely dull the blades.
Just two more things you'll need. First is a bicket of water to rinse the heads after each shot. This keeps sand from building up in the cracks and crevices of the ferrule. The other is another set of replacement blades, which you probably aready have.
The arrows will drive in pretty deep. Us old guys here used to mix in some top soil and plant grass with the sand to help holt it together,
Hey, give it a try. The worst it can do is cost you a couple bucks. Then you'll know.