Agree with you that modern day agricultural practices are the largest threat to the natural world, especially in the US. Managed hunting is not. Sport hunters that obey regulations aren't a threat to wildlife other than the few they take for the table. Getting back to agricultural practices that are harming the natural world, wouldn't land management practices, pesticides, herbicides and fertilizer runoff be the real causes?
Your personal morality isn't a good reason for taking away guns from peaceable people with no intention of harming anybody.