I own the 640 Pro, M&P 340 , and the 340PD all in .357mag. Only pistol I fire .357 out of is the 640 Pro. Otherwise the other two I only use the Speer GD short barrel 135gr +P. They are too light for .357 in my opinion. The 640 Pro I only carry it in an OWB holster. The other two I use exclusively for IWB, ankle or pocket carry. I have a tendency to carry the 340PD a lot more these days due to the weight. The 2oz difference is noticeable from the M&P when carrying all day. I'm not a revolver guy at all but I had a shoulder injury and it's the only thing I can carry and shoot reliably until my injury gets better. I like the M&P better due to the features and price but that weight difference in the PD is a big plus to me. All three of these guns I only paid under $550 each for! These are guns first timers tend to buy, shoot once and realize it's not for them and they liquidate them out. They fit a very specific purpose. All of my J frames have the Apex kits in them (Big difference) and they all have VZ grips expect the PD that has factory S&W CTC grips. The Pro I carry in a owb holster Ritchie Holster made specifically for me for that model. The M&P and PD I use an IWB Alessi Ghost for the J frame, along with Mika and Safariland pocket holsters. For ankle carry I use a vintage Renegade ankle rig and a modern Wilderness Renegade ankle rig. Hope this helps!