Try a Kytac Braveheart IWB. I had one made for my 640 and I love it. It's light weight, very sturdy and extremely comfortable. I have several Kytac holsters, mainly for my Glock 23/27.
"A man's got to know his limitations."-Harry Callahan
"Nearly all men can stand adversity. But if you want to test a man's character - give him power"-Abraham Lincoln
“...Fate rarely calls upon us at a moment of our choosing”