Not much difference. Chrome lined bore allegedly lasts longer but is less accurate. If you clean your rifle after every use it will not matter. FWIW, neither of my AR's are chrome lined. I really don't think it makes any difference. I am sure there are some who will disagree but as a civilian sport shooter I really dont get to send thousands of rounds downrange over the course of a year for it to make a difference. And the ammo I do use is non-corrosive anyway.