I'm going to buy a semi-auto. I'm leaning towards the .40's cause of balistics. Wish I could take both out and shoot them . . . but I can't.

I'm wondering if y'all think the .40 has ample knock-down power for "home defense"?

Any particular brand of gun in the .40 or .45?
There's a Ruger P90 .45 Auto with original case, extra clip for $375 at local (trustworthy) pawn shop.