I guess by now G.R.H. understands that he is using a Smith Machine. Which does not allow a natural "S" curve (as T-tones suggest), which can include most other exercise preformed on it. Major reason quite a few injuries happen with the shoulder and other body joints, tendons, ligaments. Those safety stops on the machine are not all that dependable as most people think.
Putting the exact same weight on a Smith (bar, etr weight included) and a Olympic bar you will find quite a difference. A Olympic bar feels alive, rather than the set in place Smith. Smiths do serve a purpose, but might be better avoided when using heavier or near max weight. More designed for light to moderate BB'ing, which can be a good thing. If your using 200 benching on the Smith and try using 200 on a regular bar you may be inviting serious problems. Though some guy's do short range (2" to 4") partials on the Smith. Good Luck.