I bought a 645 when they first came off the line in 1986. Figured it would be a collector's item someday as the first S&W semiauto pistol chambered for .45 ACP. I was amazed that it would feed any style of bullet - so slick it would even feed empty cases. Totally reliable. I have only three complaints. First, it's big and heavy. Second, the trigger tends to pinch my trigger finger when it's all the way back. Third, the screw on the right-hand safety lever will work loose with firing - Lok-tite will fix that, though. All in all, they were state-of-the-art semiautos when introduced, and are still fine self-defense guns today.
John