If you have to ask, you should not do it yourself. There are too many things that can be messed up. For instance, incorrect removal of the side plate can mar the gun. Screw heads can be damaged, etc.
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)