Is this a dangerous idea?

Me and my dad think it would be a great idea to...

put a shot gun bullet on this shelf that we have nailed to a tree

Then take shots at the blasting cap with a BB gun from about 100 feet away.

I personally think that it would be a great idea, its a decent distance away from windows and the shells contain training shot which is pretty tiny stuff.

I would defiantly like some suggestions though before i go sending shot flying in every direction!