[Stentor]

The key is that to use deadly force, you must have reasonable grounds to believe at the time you use it that you, or somebody you were defending, were in danger of death or serious injury.

That's pretty much also true in Pennsylvania. Here, it's probably going to depend more on getting a sympathetic county prosecutor and it's more likely that you will.

[Vanders9]

That doesn’t really surprise me. US and UK law are a lot more similar than they are different, the one is after all based upon the other. (Especially in the great commonwealth of Pennsylvania - the constitution there initially drafted by one John Locke I understand?)