Obviously this was a totally symbolic slam at legal gun purchasers.
The County Board is controlled by Chicago Black pols through a deal struck with Daley years ago: They get the County Board and they don't run for Mayor of Chicago. And the Board looks at all of Suburban Chicago within Cook County as a piggy-bank, the money to be spent on and in Chicago. The 'rich' Northwest suburbs are especially targeted.
So all this $25.00 per gun tax will really do is close down most gun shops in Cook County. Only a few had lower prices to begin with, and not by much. And this tax serves another purpose, an end run to more Gun Control.
(Cook County already has an Assault Weapon Ban that almost nobody knows about.)