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Smith & Wesson M&P .22 WMR Rimfire Pistol

The Smith & Wesson M&P 22 Magnum, chambered in .22 WMR, is ideally suited for small-game hunting or plinking.

Smith & Wesson M&P .22 WMR Rimfire Pistol

Smith & Wesson first used the term “Military & Police” for Army and Navy revolvers in about 1899. Both military and civilian models were made in 38 Special. In 1957, S&W identified its firearms with model numbers. This system continues to the present day. For revolvers, the model number is stamped on the yoke cut. The quintessential M&P revolver is what is now known as the Model 10. These are the famous K-frame revolvers.

The M&P moniker is also applied to semi-automatic pistols, beginning, I believe, in 1955 with the Model 39 in 9mm. This series now includes numerous centerfire models. Rimfire pistols began in 1957 with the Model 41 .22 rimfire target pistol.

Smith and Wesson MandP 22 Magnum in WMR, right face view
The new Smith & Wesson M&P 22 Magnum is a welcome addition to the S&W M&P family. It is chambered for the potent 22 Winchester Rimfire Magnum.

The current line of M&P pistols is extensive, and one or more models will cover just about any handgunning need. In my battery, I have M&P autos in 30 Super Carry, 9mm Luger, and 10mm Auto. All are good performers.

The New Kid on the Block

A recent addition to the S&W line is a semi-auto model that shoots the .22 Winchester Magnum Rimfire cartridge. This new pistol is identified as the M&P 22 MAGNUM. This looks to me like the perfect mating of a cartridge to a gun. It’s a chip off the old block.

The new pistol looks and feels just like you’d expect an S&W M&P to be. The frame is described in S&W literature as full-sized, and that’s a pretty good description. The weight of the empty pistol is a mere 22 ounces, and it balances perfectly in the hand. The magazine capacity is a whopping 30 rounds, and two magazines come with the gun, all packed in a fitted hard-plastic case.

Smith and Wesson MandP 22 Magnum Field Strip with Magazine
The M&P 22 Magnum in WMR easily breaks down for cleaning just like you’d expect. The parts are (from top): 30-round magazine, slide, recoil spring assembly, barrel, barrel shroud, and pistol frame.

The slide and barrel are of stainless steel, and are finished in Armornite, a hard, nitride coating that provides improved wear resistance, enhanced corrosion resistance and surface lubricity. The frame and grip are of a tough polymer that is nicely textured and provides a good handhold. The thumb safety and slide release are ambidextrous and work smoothly and positively. The magazine release is right where you’d expect it to be for right-handed shooters. However, it can be easily user-reversed for southpaws. I’m left-handed, and I had no problem whatsoever working the release with my left-hand trigger finger.

The M&P 22s have S&W’s unique TEMPO gas-operated action that keeps all parts locked up and in place until the bullet passes the gas port. (One S&W document says everything is locked up until the bullet leaves the barrel.) A minor quibble as, either way, it’s a safe and stable platform, and the barrel doesn’t cam open until the bullet passes the gas port. S&W says that the TEMPO system increases performance and aids accuracy.

Smith and Wesson MandP 22 Magnum slide, two angles
The steel slide is precisely machined.

Speaking of which, the gas port in the barrel is about .50 inch in diameter (as best I could measure it) and is about 0.8 inch back from the muzzle. Interestingly, the barrel has six circumferential rings on it, three fore and three aft, and works inside a part called the barrel shroud.

The M&P 22 WMR comes apart for cleaning just like you’d expect. First, take the magazine out, and make sure the chamber is empty. With the slide fully forward, pull the slide back about ¼ inch. Align the take-down on the slide with the slide stop lever. Then with a 3/32-inch punch, gently push the slide stop lever/takedown pin out from the left side of the frame. This can be done with two hands, but three are better. Remove the recoil spring and remove the barrel shroud and barrel proper. Clean everything and reassemble in the reverse order. This is clearly explained with photographs in the owner’s manual.

S and W MandP 22 Magnum barrel between barrel shroud (top) and recoil spring assembly (bottom).
The barrel proper is shown between the “barrel shroud” (top) and the recoil spring assembly (bottom).

The standard twist rate for the .22 LR and the .22 WMR is 16 inches. Note that the M&P 22 Magnum barrel has a 10-inch twist. This, I’m sure, is because the velocities of the relatively long .22-caliber bullets of the .22 WMR probably would not be acceptably accurate at pistol velocities with a 16-inch twist. The length of a bullet from Federal’s 50-grain load is .569 inch. (Remember, DO NOT to try to pull a bullet from a rimfire cartridge with an inertia bullet puller.) I plugged this length and its velocity (1,187 fps) from the M&P22 WMR into an online twist calculator. The stability with a 10-inch twist is rated as “stable,” but with a 16-inch twist, the program rates the stability as only “marginal.” In any event, the M&P22 gobbled up all the ammo I fed it and placed the bullets pleasingly close together, including the 45- and 50-grain loads.

The M&P 22 comes with a highly visible green fiber optic front, and a drift-adjustable rear. The .15-inch-wide notch in the rear sight makes a nice sight picture with the fiber optic front. S&W says that the M&P 22 is optics ready, and that most micro red dots can be mounted on the slide right out of the box.

Smith and Wesson MandP 22 Magnum Slide grasping groves
The back of the slide (top) has highly functional grasping grooves for easy operation. The M&P 22 Magnum in WMR comes with a highly visible green fiber optic front sight (bottom), and a properly sized notch rear sight, which is drift adjustable for windage. A set screw holds the rear sight in adjustment.

Range Results

I have had a rifle chambered for the .22 WMR for 37 years and have been impressed with the cartridge’s power and versatility. It is perfect for crop-raiding coons and other varmints, and turkeys, where legal. So, I had a good assemblage of .22 WMR ammo on hand.


The S&W literature states that it is critical the M&P22WMR should only use ammunition with jacketed bullets (JHP, TMJ, or FMJ) or the Hornady V-MAX with a polymer tip. Ammunition with copper-plated or polymer-coated bullets will not function reliably. Also, S&W says that birdshot loads will not reliably function in the pistol. Lastly, the primer sensitivity of some ammo may not function reliably either, so S&W has provided a list of ammo that they have tested and found reliable.

Two S and W MandP 22 Magnum 30-round magazines
The two 30-round magazines supplied with the M&P 22 Magnum have bright red followers.

I fired 5-shot groups at 19 yards from a padded test. (Why 19 yards? Well, a recent storm had, uh, “remodeled” my pistol range, and I had fired many groups before I noticed that I had missed the 20-yard marker under the litter by a yard.)

The Skyscreen III spacing of my Oehler M-35P chronograph was 4 feet apart, and the start screen was 8 feet from the gun’s muzzle. This puts the midpoint of the Skyscreens 10 feet from the gun’s muzzle.

I must offer two cautions. This pistol is REALLY LOUD! Be sure and wear good ear protection! Also, the ejected empties are red hot, so don’t let then slip down your shirt collar!

S and W MandP 22 Magnum magazine showing proper loading of ammo
For proper functioning, it is important to make sure that the rim of a cartridge is in front of the rim of the cartridge below it.

I tested 14 factory loads, and the accuracy and the results are shown in the load table. I think that the group sizes were excellent with open sights.

The overall group average of the 14 loads was 1.19 inches, and many were right at, or only slightly under, 1 inch. The smallest group was .73 inch with Hornady‘s 30-grain V-MAX Load. Velocity was a sizzling 1,512 fps; this is out of a 4.35-in barrel, mine you. Close behind was CCI’s 40-grain Maxi-Mag Hollow point with a .90-inch group at 1,321 fps.

My go-to load for decades has been Federal’s 50-grain JHP, Small Game Load. No. 757. (The “Bring your Own Bottle” moniker is just new packaging; 250 rounds to a bottle. The No. 757 load has been around for generations.) The velocity of this excellent 50-grain load in the M&P was 1,187 fps, and it grouped into .96 inch.

S and W MandP 22 Magnum frame showing Picatinny rail
The frame has Picatinny rail on the front for the addition of a laser or light.

The muzzle energy of these three loads exceeded 150 ft-lb. Pretty impressive for a pocket pistol.

The 22 WMR is currently touted as a round for self-defense, and specialized loads for this have been developed. Federal offers the Punch Personal Defense load with a 45-grain, nickel-plated hollowpoint bullet. In the M&P, it clocked 1,236 fps, grouped into 1.32 inches, and produced 153 ft-lb. of muzzle energy. Another excellent defense round is Hornady’s Critical Defense load with a 45-grain FTX bullet. It registered 1,260 fps, and produced 159 ft-lb. at the muzzle in the M&P. Then there’s always the Federal 50-grain load.

Actually, I think that a couple of any of the .22 WMR rounds would ruin a bad guy’s day, or deter a feral dog or rabid  ´coon. I have “relocated” many vineyard-raiding raccoons with the Federal 50-grain and Hornady’s 45-grain load. Both are totally effective.

S and W MandP 22 Magnum Plastic Storage Case
The M&P comes in a sturdy, fitted hard plastic case.

The magazines that come with the M&P 22 WMR hold 30 rounds, but for testing, I only loaded five rounds of each factory load. When I got to the third round in the magazine, it would occasionally fail to chamber. Since rounds one and two fired and ejected, the slide was forward on an empty chamber. This, of course, resulted in a “dry fire,” something not recommended for any rimfire, and specifically discouraged in the Owner’s Manual (Page 29), as it can damage the pistol. However, this malady seemed to happen less frequently as I put more rounds through the gun, so maybe it just needs some more breaking in. I suspect that this is a passing idiosyncrasy of this particular gun.

One statistic I use to assertain uniformity in velocity data is what’s called the “coefficient of variation” (COV). This is just the standard deviation expressed as a percent of the average velocity. It provides a good apples-to-apples comparison of loads. Generally speaking, any COV under 2% is pretty good, and around 1% is really good. Well, some of the loads had COVs over 2%, and three were over 3%.

Smith and Wesson MandP 20 Magnum Slide Cutout for Optic
The M&P 22WMR is “optics ready,” and the rear of the slide has a cut out for the addition of a micro red dot sight. No adapter plate is required.

The 22 Winchester Magnum Rimfire Cartridge

The introduction of the 22 WMR was a significant development for rimfire arms. Its introduction markedly improved the power available to .22 rimfires, as well as maintaining its versatility and accuracy. It has been a resounding success, as today, almost all rifle makers have models for the .22 WMR, and ammo companies offer a variety of .22 WMR loads. For example, Winchester offers 10 loads, Remington 3, Federal, 3, and Hornady, 2. So the .22 WMR shooter has plenty of excellent loads from which to chose to match the shooting need, be it plinking, pest control, or varmint hunting. Bullet weights for current loads range from 30 to 50 grains.

Until recently, handguns for the .22 WMR were mostly limited to excellent revolvers from Ruger and Smith & Wesson. A void was the lack of suitable semi-auto pistols to fire it. Attempts to develop semi-auto pistols to fire the .22 (WMR) have met with varying degrees of success. The longer and more powerful .22 WMR offered some mechanical challenges for reliable operation. The .22 WMR delivers considerably more velocity than the .22 Long Rifle because the case is longer, and it uses more powder. The WMR case is 1.055 inches in length, while the .22 LR is a flat 1-inch long. And the diameter of the WMR body is .242 inch; for the .22 LR, it’s .226 inch. Interestingly, the S.A.A.M.I. Maximum Average Pressure (MAP) for both cartridges is 24,000 psi. But just as in the good ol’ days, Smith & Wesson has brought forth a new model that fills this void under the trusted M&P banner.

Selection of .22 WMR ammunition from various manufacturers.
There is an excellent selection of ammo for the .22 WMR, with bullet weights from 30 to 50 grains. It is important to use only loads with jacketed bullets. Plated or lead bullets will quickly foul the barrel shroud. Also, shotshells are not recommended for this pistol.

Many shooters will recall the 22 Winchester Rimfire (WRF) that was developed for the Winchester Model 1890 pump-action, and later M-1903 semi-auto rifles. It fired 40- or 45-grain bullets and was the first notable improvement in ballistics over the .22 LR. The round and the rifles that fire it are now obsolete. “Cartridges of the World” states that the “.22 WRM can be safely fired in any gun chambered for the .22 WMR.” This was written, of course, before the M&P 22 WMR was introduced.

The names of the two cartridges are confusingly similar, but I would caution against trying the .22 WRF in the M&P. For one thing, it shoots a plain lead (e.g., unjacketed) bullet, a major no-no. Plus, the round is only 1.1804 inches log, and the neck diameter is .243 inch. The .22 WMR is 1.328 inches long, has a neck diameter of .239 inch. Plus, the MAP of the .22 WRF is 19,000 psi, 5,000 psi lower than for the .22 WMR. Thus, for a variety of reasons, the 22 WRF should not be fired in the new M&P 22 Magnum pistol.

Shot Groupings for the SandW MandP 22 Magnum in .22 WMR
All of the loads tested delivered acceptable accuracy. Here are some examples: Top left: The Federal 50-grainJHP load has been around for years, and is not only accurate but powerful, at 156 ft-lb. Top right: The Hornady 30-grain V-MAX varmint load registered 1,512 fps, and delivered this nice, round group. Bottom left: Remington’s 40-grain JHP was accurate, and delivered the highest muzzle energy of all loads tested, at 163 ft-lb. Bottom right: Shooting produces a lot of empty cases.

Summing Up

The new S&W M&P 22 WMR is the queen of the ball. It is a fine cartridge-handgun combo. It will take care of most pest control and small-game hunting situations. It is accurate and a great plinker; tin cans quiver at the mere mention of its name. I like all of my M&P pistols, but the new 22 WMR is a real gem. I like it. I bet you will, too. It’s a keeper.

Author Steve Gash and a raccoon he took with an SandW MandP 22 Magnum in .22 WMR.
Author Steve Gash shows off a raccoon he took with the Smith & Wesson M&P 22 Magnum in .22 WMR.


  • MANUFACTURER: Smith & Wesson,
  • TYPE: TEMPO gas-operated semi-automatic, internal hammer-fired, locked-breech
  • CALIBER: 22 Winchester Magnum Rimfire
  • MAGAZINE CAPACITY: 30 rounds
  • BARREL LENGTH: 4.35 inches, 10-in. twist
  • BARREL MATERIAL: Stainless steel with Armornite finish
  • SLIDE: Stainless steel with Armornite finish
  • OVERALL LENGTH: 8.4 in.
  • WIDTH: 1.13 in.
  • HEIGHT: 5.9 in.
  • WEIGHT, EMPTY: 22 oz.
  • FRAME: Full size, black polymer, slim, textured grip, Picatinny rail for accessories
  • SLIDE RELEASE: Ambidextrous
  • SIGHTS: Fiber optic front (green), adjustable rear notch, sight radius 7.0 inches, optic ready
  • TRIGGER: Flat-faced, Pull weight 4.64 lbs.
  • SAFETY: Ambidextrous manual thumb safety
  • ACCESSORIES: Two, 30-round magazines, Instruction Manual, fitted hard plastic case
  • MSRP: $649


  • "History of Smith & Wesson" by Roy Jinks, 1977, p. 159.
  • "Standard Catalog of Smith & Wesson, 3rd ed." by Jim Supica and Richard Nahas, 2006, p. 143.
  • "Cartridges of the World" ed. by Richard Mann, 13th Edition, 2012, page 496.

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