dubbletoast
With some testing, I've found brass does not make very good crossbows. I stood about a building's length away from a window in Port Town and fired at the center of it with two different crossbows. While the all-plutonium crossbow landed a bolt just inches below the target, the all-brass crossbow's bolt didn't even make it to the wall.
Edit: The brass crossbow I made is up for sale at the shop for the low, low price of 400 gp. It's so stuffty I couldn't live with myself if I sold it for any more.