Computer Aided Design (CAD) and computer simulation are now being used extensively, which significantly shortens development time. For example, previously each design iteration takes 6-12 months; now it takes only 1 month. Moreover, accurate simulation software and increased compute power allow designers to crunch out a simulation (of a gun's action) in 30 minutes and validate a design in a single day, which used to take weeks.
Shown here is a computer simulation of a pistol being dropped on a hard surface. The simulation is used to quickly solve an accidental discharge problem that previously would have taken months to resolve.