Surprisingly, the barbell bench press doesn’t stimulate muscles that much. This statement is based on EMG studies. However, there are ways to make it more effective.
The best reason to bench press with a bar isn’t necessarily to build pecs but for hormonal release. Big bang movements like the bench press increase testosterone and growth hormone concentrations, which will help hypertrophy everything, not just your chest and triceps.
So if the goal is to grow, then bench with a bar, but to target the muscle fibers of the pecs more directly, you need more. Here are two great exercises:
Standing Cable Chest Press
The chest doesn’t get any downtime with this exercise. The tension is constant, and tension is one of the keys to hypertrophy.
Since the cables are placed above shoulder level, the pecs have to do serious work to keep the cables down (pec minor), and perform a press forward (pec major). Make sure the elbows still travel straight forward and back.
Dumbbell Low Incline Bench Press
Set an incline bench on its lowest incline and grab some dumbbells. You’ll get more range of motion, integrity of movement at the elbow joint, and tremendous stimulation of both sternal and clavicular pecs due to the seat angle. You can’t get any better than that.
This is a great exercise for major chest development, provided your shoulders don’t give you grief on a regular basis. Plus, you can still go damn heavy.