From what I have read concerning your problem, and if they are truly stray, or feral cats, the only way to get rid of them is to trap and relocate the animals.
Living outdoors for most of their lives a paintball or pellet will not take them away from getting their food. Also, you will not be out there 24 hours a day to shoot at them, so they will come back.
Have you tried calling whoever is in charge of your neighborhood/complex? They will probably not see this as a very pleasant thing to put up with.
Not sure if you have called them, but I found this:
If you are searching for help with a dog or cat issue, you need to call your local Franklin County animal control or SPCA. They can assist you with problems such as a dangerous dog, stray cats, lost pets, etc. There is no free service in Franklin County that provides assistance with wild animals.
Franklin County Animal Services, OH: (614) 462-4360