Here are my own observations FWIW: I recently purchased a new 640 to replace my tested-to-destruction ruger LCR .357. A little about the ruger.
Surpisingly comfortable to shoot with the little hogue bantam grips and full power .357 mag loads. I guess there is something to be said for the polymer "fire control housing" absorbing recoil. By tested to destruction, I mean the cylinder began to drag after about 1200 rounds. After sending it back, Ruger sent me a new one which I proptly sold.

Now I'm a fan of pocket carry. And while revo's tend to be bulky compared to most of the little mouse guns, Reliability and Power make up for this IMHO. For a replacement for my LCR, I strongly considered the S&W 340. Its light weight is really appealing to me. However, I was put off by the reports of almost uncontrollable and painful recoil with .357 mag loads and the fact that most guys ended up carrying .38 special in them. I'm also someone who shoots alot. Like 800-1000 rounds of .357 a month (mostly in my 686, but I also practice frequently with my carry guns). I'm not convinced that the airweight alloy revolvers can hold up to heavy use any better than the plastic frame LCR did.

Enter the 640. 23 oz empty is a bit on the corpulent side for a pocket gun, but it is every bit as concealable as any other j-frame in spite of its extra 1/4" of barrel length (as compared to the 340 or my 642). One thing I didn't like about it was the factory plastic grips. Way too big and bulky. I ordered a set of smooth classic (wood) panel grips that are very dainty and ideal for a tight pocket. They also look really pretty compared to the ugly stock grips.

A big plus for me besides the added concealability of the panel grips is the fact that I'm actually able to get three fingers on it since I'm gripping further up into the "horn" area than most of the other compact grips on the market allow. I also imagine that a higher grip leads to potentially better control of muzzle flip. However, there is a problem: When I loaded it up with Double Tap Bonded Defense 158 grain loads (I chronoed at 1260 FPS BTW) I was in for a rather unpleasant surprise. The felt recoil was so bad I almost did not want to finish the cylinder. DoubleTap Bonded Defense S&W 640 - YouTube


For me the main point of discomfort was where the backstrap met the web of my thumb. I would like to retain the compactness and looks of the wood panel grips. Does anyone have any ideas of ways to cover the backstrap with a little padding that would not look too hokey? I'm thinking of experimenting with glueing a strip of rubber or something back there.