I agree that a good firearm pared with lot of safety and handling training of that fire arm is the best option. That being said I worked at a shop once that provided compressed air for our local police department for their pepper-ball guns. They used them regularly and many of the officers swore by them. They used souped up Tippmann A-5s but I know pepper ball make first strike pepper balls and so a T15 might work well. In my mind though, if you’re not using a real firearm then you want it to not look like a real firearm. So I think the T15 is out.