I understand there are some differences still it's a derivative work, the bastard lovechild of a paintball and a foster slug. I'm not trying to denigrate Tom's work I just see it as an obvious adaptation of existing technology. That and I'm opposed to the notion of ownership of an idea.
Regarding spin stabilization vs fin stabilization, the jury is still out. All I know is FSR maintain velocity better and yield tighter groupings which is enough to get my $.