The trigger should be clean and crisp, with no creep, and set for 3.5 to 4 pounds. The barrel and frame should be throated and ramped to feed all ammunition. Options such as ambidextrous safeties, extended slide releases, and beveled magazine wells are matters of personal preference.
However, the frame should be designed to properly fit the shooter's hand. This can be achieved by utilizing a short or long trigger and a flat or arched main-spring housing with appropriately sized grips.
If the firearm has been set up properly, it will feed, chamber, and operate with any type of ammunition loaded into it.
Editor's note: Bruce Park also contributed to this article. Park is  the senior armorer and a reserve deputy with the San Bernardino County  (Calif.) Sheriff's Department. Park is certified as an FBI and NRA  Police  Firearms Instructor, as well as an FBI Armorer.