either move your grip in, or learn how to tuck your elbows on your decent rather than flaring them out and touching really high on your chest. This places tremendous strain on the shoulders and is how alot of lifters get hurt. Tucking your elbows and touching your sternum will transfer the majority of the weight off your shoulders and onto your back (yes back), tris and chest. Moving your grip in will make you do this almost automatically(ever notice that your shoulders dont really hurt when doing closegrip bench?), but it can be done using a wide grip also with practice.
And yes if you want to call it a proper benchpress, you do HAVE to touch your chest. Those guys at your gym probably get annoyed with the fact that they have to watch you butcher a basic movement like the benchpress every time they see you do it. And i was using 100's when i was 17 and 160lbs, big deal, if you learned how to benchpress properly, you could move alot more than that. If you can get a full range of motion with DB's, you can do it with the bar. Seriously take my advice and just try it next time your going to bench. Just think on your decent, tuck your elbows in towards your ribcage, flare your lats, and bring the bar to the lowest part of your sternum. TRY IT!