My Commercial Sales manager had an incident just like that. About 2 months ago, a thief broke into his car and stole a about $2000 in stereo equipment. 2 weeks ago, a thief (probably the same guy, but police can't interview him yet since he still can't speak) broke into his car and was attempting to steal it. My CSM ran out and beat him with a golf club until the police showed up. When he stopped swinging the guy just oozed out of his car onto the concrete, and was limp when he was taken to the hospital. Big old blood spot in the drive way, and blood all over the car.
The PG cops told him if he killed him it was manslaughter, however as it stood it was self defense. Got to love MD laws.
I have to agree with Gylius in principle. Yes, I would be pretty fucking pissed if someone was attempting to steal my shit for the second time in two months. And I would swing a bat or golf club to bring them down. But 30 seconds with a golf club is a long fucking beating.
If it were me, absolutely I'd swing more than once. I don't know if he's on drugs and I don't want to be known as the guy killed with his own baseball bat trying to fend off an attacker. But after the guy goes down, and you know he's down, then just. stop. hitting. him. Of course right after I would surely break his knees/hands so he never stole from anyone ever again. But that isn't life threatening.
As for the shooting, it would be much easier to kill someone with a pistol. I applaud you for having the nerve and focus to aim for his leg. I'm positive my hands would be shaking too much to aim for anything but center of mass. And if he's rushing towards you inside your own house (<10 yards), that first shot better count.