In real life nothing. In courtroom that is a huge difference. A DA will twist and turn everything to make you look like a gunslinger. A modified gun is more lethal in the DA's eyes. Massad Ayoob is one of the leading authorities on the subject. He preaches the doctrine that modification leads to liability for LEOs and civilian gun owners. His articales are worth a read. http://thetruthaboutguns.com/2011/01/brad-kozak/the-massad-ayoob-chronicles-part-v/ ...Generally, as a rule of thumb, anything that will make the gun shoot better for the shooter under extreme stress and poor light is absolutely defensible. And the reason is, if it makes you more likely to hit under those adverse conditions, it concomitantly reduces the danger of a wild shot that might hit a bystander. The two things I would strongly advise against doing and have strongly advised against doing, would be a trigger pull lighter than the factory recommends, and removal or de-activation of a safety device. You try not to give weapons to your opponent. If I have an [opposing] attorney trying to nail my scalp to the wall, I’m not gonna give him the sound bite of “Ladies and gentlemen, you’re here to determine whether this man was reckless, and arrogant, and negligent. Ladies and gentlemen, he was so reckless, he deactivated the safety device on a lethal weapon. And he was so arrogant, he thought he knew more about this gun than the designer.” Tell me how you’re gonna get past that. As far as the light trigger pull, your problem there, number one, is it has historically been linked to unintended discharges. So problem one, under stress, we SAY we’re gonna keep our finger off the trigger. The trouble with that study done in Europe with trained emergency-response personnel, indicated that several times, the sensors that were put on the test gun picked up a finger touching it [the trigger], when the officers swore that during the high-stress exercise their finger had never entered the trigger guard. It apparently occurs unconsciously, as the mind says “Hey, if we have to shoot this thing, we want to verify we can reach the trigger.” Second, you can go to court and say “I didn’t accidentally discharge the gun, I always keep my finger outside the trigger.” And they will then hit you with the bomb. “So, you want this jury to believe that you’re incapable of making a mistake? You’re the first perfect human being in two thousand and ten years. Is that what you’re telling this jury?” Now that is gonna be a pretty tough sell... It's your ass. Cover it how you see fit.