Actually copyrighting the logo would do nothing -- you would first have to identify that this was original work and that you were the artist and that you would be damaged if the image was used without your permission.
In order to be protected, it would need to be registered as a trademark and then they have protection as a "propriatary image" that represents them. But that costs bucks, and face it, its a paintball team and not a corporate logo or anything like that. There would be no way to demonstrate in court that you are being damaged by the "infringement" of your trademark.
Lastly, if the picture, or some reasonable facsimile is in the public domain, then anyone can use it.
Be as pissed as you want, but that is the hard cold truth.
Just a quick google search:
So if you want to be technical, your friend's team is in actuality in infringement of a registered image from another source.
Bummer