I think it's something else.
You surely can't find any ip.bin because your game is selfboot. But there's a way to get it (there's a lot of tutorials around). Anyway, it won't help you : I already tried to change all country checks and "gun" check box. It didn't do anything.
I would be surprised if PAL Patcher worked for that kind of patch : I wrote it, and already tested it for guns problems.
I think there's something with TV's display settings. I don't know how guns work, but I think they can get the lines scans and then calculate the right position. So if the refresh rates change, or something like that, it won't work.
But I don't know how they detect your gun at startup...