My short answer to your question is: No handgun and load is going to be as effective as a shotgun. Therefore, do not depend on, or expect any handgun to stop a human attacker, load them down with as many bullets as you have got in the gun...double-tap, triple-tap, quadruple-tap, till empty.
Sometimes you get what you pay for, sometimes you only pay more for what you get.
Three shots are not a "group"...they are a "few".
If the Bible is the literal, infallible, unerring word of God...where are all those witches I am supposed to kill? (Exodus 22:18)