Do I get the .40 or 9mm? Can the .40 be converted to shoot 9mm? Have the mag drop issue's been resolved yet? Is there anything I should be aware of before I purchse one? I have owned one before in 9mm but was curious on the .40 and if any issues had arrived on the newer serial #'s that I may not know about.Oh yea, I also have a Glock 19 if that helps any.