Smith & Wesson 340 M&P Lightweight Centennial .357 Magnum Revolver


by Jeff Quinn

photography by Jeff Quinn & Boge Quinn

August 24th, 2007




Everyday, I get requests from readers to recommend a good handgun to carry concealed. With more and more states now allowing citizens to exercise their God-given and Constitutionally-guaranteed right to self protection without fear of government prosecution, more people are now carrying firearms. That is a good thing. Most new pistol packers, however, choose a handgun that is too large to comfortably carry on a daily basis. After packing the big gun for a few days, they start to leave it at home, or in the truck, only carrying it when they think they might really need it. The first rule of a gunfight is to have a gun. If you canít reach it, you lose. A person is much better off to select a handgun that will be with him (or her) always, than to choose too large or heavy a gun, and it not be within reach when it is needed. If you are ever forced to defend yourself, it will happen very quickly. Remember, the attacker has had plenty of time to carefully select his target and plan the attack. The victim is usually taken by surprise. The gun has to be within your reach, or it is of no use to you. It is natural to want to carry a handgun that is more powerful than some of the smaller handguns that are available. However, in a fight, any handgun is a compromise. If I know that I am heading for a fight that I canít avoid, I will carry a rifle or shotgun. Like most of us, I canít conveniently carry a long gun everywhere that I go, so I carry a handgun. I have several pistols and revolvers from which to choose, from .22 rimfire pistols, all the way up to the .500 Magnums. Any would be a pretty good choice in the right circumstances, but for everyday, everywhere carry, my choice is a five-shot Smith & Wesson .38 Special loaded with Plus P Cor-Bon Glaser ammo. Like I stated above, it is a compromise, but it is the best compromise that I have found. My particular carry gun is the Centennial Model 342PD, a handgun which is now out of production. The Centennial is often called a "hammerless" revolver, but that is not correct, as it does have a concealed, internal hammer. The beauty of the design is in its simplicity. The hammer being concealed, it cannot snag on anything coming out of the pocket. There is but one mode of fire, and that is double action. Pull the revolver from the pocket and go to work. No safeties or switches to manipulate. Point the gun and pull the trigger. Simple. The 342PD is of aluminum, stainless steel, and titanium construction. The aluminum frame is strengthened with scandium. This combination of materials allows for a very light weight handgun. As stated earlier, the 342PD is now out of production, but S&W has a new revolver that is everything that the 342PD was, and more. It is the 340 M&P .357 Magnum Centennial revolver. Smith & Wesson markets their M&P series of rifles, pistols, and revolvers towards the military and law enforcement, but they work just as well for the rest of us, and any Smith & Wesson dealer can order them for you.

Weighing just about two ounces more than my pocket gun, the 340 M&P comes with the XS Tritium sight that is pretty close to the one that I added to mine a few years ago. The rear sight notch is also larger on the new M&P, to better match up with the larger tritium front sight.  The 340 M&P has a blackened stainless steel cylinder instead of titanium, accounting for the slightly heavier weight. The 340 still weighs in at a svelte 13.3 ounces. It has a stainless steel barrel that measures just under one and seven-eighths inches in length, and wears an aluminum shroud that also covers the ejector rod. The barrel/cylinder gap on the test gun measures just four one-thousandths (.004) of an inch. The trigger pull is a smooth but slightly heavy nine pounds, seven ounces.  The compact five-shot cylinder has a diameter of 1.308 inches, and a length of 1.597 inches.  The overall length is just under six and one-third inches.

The grip on the 340 M&P is a very compact and comfortable Hogue unit, just like the one that was on my 342PD when I got it. It works very well. Firing full-power .357 Magnum ammunition, the gun was very comfortable to shoot. Recoil is there, mind you, but there was no pain at all, and the gun was easy to control. The 340 shot slightly to the right for me, as I expected. With the double action trigger pull and my large hand, I push slightly to the right with a small grip, being a left-handed shooter, when firing quickly.  On my personal gun, I installed a set of Crimson Trace Lasergrips which are larger, covering the backstrap and adding about one-quarter inch to the trigger reach. That corrects the problem for me. It does add a bit to the bulk of the handgun, but also has the benefit of the laser for shooting in the dark. As stated above, every gun is a compromise. If your hand is of small to normal size, you will love the grip on the 340 M&P. If your hand is large, it still might work very well for you. It is probably the best factory-supplied grip on any small, lightweight revolver available today.

Choosing the right ammunition is every bit as important as choosing the right handgun for social work. If carrying a full-sized 1911 .45, just about any ammunition will do the job. With smaller calibers, I get a bit more picky. I really like Cor-Bon Glaser ammo for a carry revolver. I have carried my .38 Special loaded with nothing but Glasers since I bought the gun. I have shot snakes, crows, one beaver, and a few other animals with the Glasers, and have been impressed with the results every time. Hopefully, I will never need to fire the gun in defense of my life against another human, but if I do, I want it loaded with Glasers. They are expensive, but they are worth it. I also like the Cor-Bon PowRBall in the 340 M&P, but prefer the Glaser. Whether the M&P is carried loaded with Plus P .38 Special or .357 magnum ammo, I know of no better choice, and until proven differently, mine will carry Glasers. The 80 grain .357 Magnum Glasers scream out of the short barrel at 1515 feet-per-second (fps). The 100 grain PowRBall .357 Magnum loads clock 1477 fps. Looking at the fired primers in the picture reveals that Cor-Bon loads their ammo hot, but functioning was perfect in the little Smith. The benefit of shooting these lightweight but high velocity loads out of the 340 M&P is that they are very controllable for fast follow-up shots. Shooting offhand rapid fire at 25 yards, keeping either of these loads on a standard human silhouette target is easy. At seven yards, keeping a cylinder in the face of the silhouette was very simple to do. The sights on the 340 M&P are the best that Smith & Wesson has ever put on a self-defense J-Frame. The front is bright and easy to see, and the rear notch is large and quick to align. As seen in the pictures, the sights on the new gun are much better than on my older Centennial.

There are many good holsters on the market for a J-Frame Smith, but to me, the 340 is a pocket gun. I carry mine in my left front jeans pocket, and it hides very well. It is easy to reach, and even walking around with your hand in your pocket draws no unwanted attention. Same with a jacket pocket. You can have your hand on the revolver in your jacket pocket, and cause no social problems by doing so.  If needed, with the enclosed hammer, you can even fire through the pocket.  Another great benefit of the enclosed hammer is that no dust, dirt, grit, sand or pocket lint gets into the action of these guns.  Mine has been covered in all kinds of dirt and sweat, and fires reliably every time, with literally no maintenance at all. It always works.

Because there has been so much discussion on the topic on the internet forums, letís discuss the internal key-lock safety on the new Smith & Wesson revolvers. I do not use them, and would be perfectly happy if the guns did not have them, but they are here to stay, and cause no problems. If you want to use it to secure your gun when it is out of your reach, it is there. If you think that a kid or stranger might touch your gun when you have to leave it at home for some reason, like when flying on commercial aircraft, use it. If you donít want to use the lock, just ignore it. I always hear of some guy, who knew a guy, whose cousinís friend had the lock to activate itself, but have never yet heard from anyone with first-hand experience with this. I have several of the S&W revolvers that have the key lock, and have never had a problem. My 342PD that I carry everyday has always fired without fail anytime that I have pulled the trigger. I trust my life daily to the little gun, and do not worry at all about the key lock. If it bothers you, take it out and throw it away, or grind off the cam, but it is crazy to let the key lock stop you from buying the best pocket revolver on the market.

There are many good, reliable, compact, and lightweight handguns for personal protection available today. If you like a semi-auto, the choices are plentiful. If you prefer a revolver, there are a few of those available also. However, in my opinion, none are better than the lightweight .38 and .357  Smiths. As stated before, it is a compromise. The five-shot cylinder does not have the capacity of larger revolvers, but the smaller size makes it lighter and more concealable. The short barrel does not lend itself to shooting tiny groups on paper at long range to impress your friends, but again, it makes the gun easier to hide. Not having a hammer spur does not allow for precise, carefully aimed single action firing, but the enclosed frame keeps grit and debris out of the revolverís action. Change one feature and you compromise another, but the S&W lightweight Centennial balances everything into a very nice package for up close and personal social encounters of the most unfriendly kind. This is the gun that I recommend more than any other for those who want a compact, reliable, powerful, and easy to use handgun for daily concealed carry. Sometimes I carry a larger handgun in a belt holster, but always in addition to, and not instead of, my Centennial Smith. It is my choice for personal defense as my everyday, everywhere handgun.  I trust it to protect my life. I cannot recommend any handgun any higher than that.

Check them out online at

To order Glaser and other Cor-Bon ammunition, go to

Jeff Quinn

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Click pictures for a larger version.


Smith & Wesson 340 M&P Lightweight Centennial .357 Magnum Revolver.



340 M&P comes with S&W hard plastic case.





The 340 M&P (top) compared to Jeff's daily companion, the 342PD (bottom).



Compared to the medium-frame six-shot Ruger Service Six, the handy size of the 340 M&P is readily apparent.



The 340 M&P compares favorably with Kel-Tec's compact PF-9 9mm semi-auto pistol. What the M&P gives up in firepower, it more than makes up for in stopping power.



The 340 M&P features a stainless barrel with an aluminum shroud.





Comparison of the sights between the 340 M&P (top three pictures and at right on second picture from bottom), and Jeff's 342PD (bottom picture and at left on second picture from bottom).



Soft rubber Hogue grip is small and excellent in design.



The one-piece grips are removable with the aid of an included grip removal tool.





Smooth trigger is an aid in double-action shooting.





Like it or not, S&W's key-locking mechanism is here to stay. Jeff chooses to ignore it, but it does not bother him.



As befits its "Military & Police" name, the 340 M&P incorporates a lanyard pin in the butt.



The 340 M&P is small enough to carry in a jeans pocket unnoticed by the outside world, and lightweight enough to be unnoticed by the bearer.



Two of Jeff's favorite carry loads for the 340 M&P.



The 340 M&P loaded with Glasers.



As the spent primers indicate, Cor-Bon is some hot ammo.



7-yard (top) & 25-yard (bottom) offhand rapid-fire groups show the 340 M&P is plenty accurate for its intended purpose.