Smith and Wesson brought out a brace of 9mm handguns in 1980. The 2nd generation of autos was introduced with the Models 439 and 459. These were anticipated and appreciated, but the other 9mm they brought out was not expected at all–it was a revolver.
The new Model 547 revolver was built on the K-Frame, and equipped with fixed sights on the heavy bull barrel. It sported a blued finish, and was offered with either a four-inch barrel and square butt, or as a three-inch round butt. The square butt version wore conventional Magna service grips and weighed 34 ounces. The round butt came with unusual, walnut target grips with a speedloader relief cut on the left panel, and weighed in at 32 ounces. The front and backstrap lacked serrations, but the 1/8” front sight did not.
They came with nicely case-colored triggers and hammers. The well designed, smooth faced combat trigger measured .312” wide. The hammer was a service style, measuring .265” wide. It differed from a normal M&P hammer as it was “semi-bobbed,” and was visually shorter in length. Thumb cocking it revealed a flat front with no hammer nose; The firing pin was mounted in the frame. The barrel rode over a non-shrouded extractor rod and was scribed with “9MMCTG. PAT.4127955” on its right side. The cylinder was fluted and shared the length of a K frame .357 Magnum cylinder at 1.67”. At first glance, it looked like a Model 13 with a shortened hammer.
The French connection
Writers of the day suggested that the Model 547 was developed in response to an inquiry from the French government, in the late 1970’s, to provide a 9mm revolver for police use. One of their requirements was a revolver that could function with the rimless 9mm round without using moon clips. Roger Curran, who was the Director of Research and Development at S&W at that time, led the project.
At some point, the French reconsidered and took a different path. Curran had invested a lot of time and resources in the project and drove on. After three years, the 547 was introduced to the United States commercial market. It was no easy task getting it to work right without moon clips. Curran’s team came up with some incredibly innovative ways to make the 547 function like the French had originally requested.
Under the hood
The unique looking hammer, and what was going on underneath it, was critical to the successful function of the gun. Hardcore S&W folk will note the 547’s frame mounted firing pin showed up about 20 years before “normal” S&W revolvers got theirs. This engineering change didn’t occur until 1997/1998 for most other models. It was used in the 547 along with some other parts to deal with the complexities of operating with the 9mm cartridge.
Revolver cases use their rim to achieve proper headspace. On an auto cartridge, the case headspaces on the forward edge of the case in the charge hole chamber. The 9mm was loaded all over the world to vastly different pressures and case length variations. Add the slight taper inherent to the case and it makes cases very prone to backing out of charge holes upon firing. This leads to pierced primers and case heads smashing into the recoil shield. It can impede cylinder movement and even lock the cylinder up. Smith & Wesson engineers were used to dealing with this problem, because of the Model 53 revolver and its bottlenecked .22 Jet round. The headaches with the Jet led to solutions that worked well in the 547.
The engineers designed and installed a patented “limit pin” directly above the firing pin in the frame, both of which were spring loaded. When the hammer falls on a 547, it drives both the firing pin and the limit pin through the bolster (“breech,” in S&W-speak) face. The firing pin strikes the primer, and the limit pin bears on the cartridge’s head, limiting case set back. The force from the case setting back actually transfers through the limit pin, and forces the hammer rearward. This allows the firing pin to move away from the primer, and prevents primer piercing. The rearward movement of the hammer can be significant, depending on the pressure of the ammunition, which is why the hammer spur was bobbed—shortening it decreases the probability of the spur pinching the web of the shooting hand, in recoil.
The 547’s firing pin is also unusual. It travels through the bolster face at full diameter, but steps down with a sharp shoulder to form a smaller diameter tip. The hammer delivers a lot of force to the firing pin because of the more powerful mainspring in the 547. The strain screw is also longer to provide more tension on the spring. These modifications were necessary to guarantee ignition with the hard primers found in some military surplus ammunition. The limit pin controls the depth of the hard strike delivered by the firing pin. Smith & Wesson engineers estimated that the gun would pierce up to 80% of primers on some types of ammo without the limit pin.
The trigger pull is smooth, like all K-Frames of that era, but it’s heavier than normal, due to the beefed-up mainspring and longer strain screw—fourteen pounds on average for the double action, and three to five pounds for the single action pull. You can feel the extra pounds when you thumb cock one–it’s noticeably harder than a Model 10.
Extracting every bit of performance
The other perplexing problem with revolvers that fire auto pistol cartridges is extracting the rimless rounds. Moon clips give a conventional extractor something to grab onto (in addition to providing correct headspace), but the French buyers didn’t want to use them. Out of the box thinking was required to solve this problem.
Curran and his team came up with a unique extractor, as a solution. The head and stem of the extractor were investment cast from beryllium copper. The copper was chosen for its low coefficient of friction and was heat treated to the same strength as steel. It also demonstrated excellent resistance to wear in testing. Each charge hole had a small spring steel leaf that fit in a groove when the extractor was at rest. With the extractor seated fully in the cylinder, cartridges could be dropped into charge holes as normal, because the extractor leaves were retracted. When the extractor rod was pressed, the end of each leaf expanded into the extractor groove of the case, allowing the extractor to push the case out of its chamber. Engineers were satisfied with the strength of the system and claimed the portion of the leaf that engaged the brass case head would tear completely through the brass without breaking.
A welcome benefit of this type of extractor system was the elimination of dreaded failure-to-extract stoppages, where the rim of a revolver case becomes lodged underneath the extractor star. There was no extractor star! If a case failed to extract, a shooter would simply allow the extractor to return to rest, and try again. The steel leaf would compress past the case and give you another chance.
Industry testing demonstrated that the 9mm was ballistically superior to .38 Special loads of similar bullet weight. On paper, 124 grain 9mm’s would best 125 grain +P .38’s by over 100 fps from equivalent barrel lengths. Another advantage–that was counter intuitive, and ran against traditional thought–was that the revolver actually produced more velocity than a semi auto of equal barrel length, with the same ammunition.
It was always assumed that the barrel-cylinder gap of the revolver would rob velocity and make it suffer in comparison to the solid barrel of a semi auto. The .357 Magnum-length cylinder gave almost 9/10 of an inch of “free bore” at the front of the cylinder, from the point that the chamber ends. After leaving the case, the bullet had room to accelerate prior to reaching the barrel-cylinder gap, the forcing cone, and the resistance of the rifling. The same round fired from a semi auto chamber will encounter rifling, and therefore resistance, before the bullet has even fully left the case in most chambers.
I chronographed some ammo through a 3” Model 547 a while back, along with a 4 ¼” barrel S&W M&P Auto, and velocities were very close. The 547 recorded higher velocity than the M&P with one round out of the four tested. I decided to repeat this test using semiautos with barrels closer in length to the 547– a Shield with a 3.1” barrel, and a Model 6946 with a 3.5” barrel. Rounds were fired across a Pro-Chrony Chronograph, 12 feet from the muzzle. The temperature was 83 degrees Fahrenheit at an altitude of 5,600 feet above sea level. Five-round strings were fired with each of these common bullet weight factory loads, with the following averages:
The 547 turned in the highest velocity of the three guns, with four of the five rounds tested. A S&W Model 65 3” was used to test .38 Special and 357 Magnum loads for comparison to the 9mm ammunition:
The 9mm 147 grain topped the .38 Special 147 grain, even though the .38 was a +P+ loading, and the 9mm was loaded to standard pressure. The 9mm SAAMI pressure ceiling of 35,000 psi certainly helps it in this contest, as it can operate at double the pressure of standard .38 ammo.
The 9mm completely outclassed the .38 Special with 124/125 grain bullets. The Winchester Ranger +P 124 grain bonded JHP bested the .38 +P Remington Golden Saber by a whopping 260 fps. When fired through the 547, this round lands solidly in mid-range .357 Magnum territory, as evidenced by the .357 Golden Saber velocity. The 125 grain .357 Magnum DPX load is about the high end for a reasonable carry load (for me), in a 3” K frame .357, but only outruns the 9mm Winchester Ranger 124 +P by about 100 fps. The old Remington 125 grain JHP is much faster, beating the 9mm by a wide margin (247 fps), and is one of the rounds that made the fearsome “one shot stop” reputation of the .357 Magnum. However, its viability as a carry load is limited in a gun this size. With respect to recoil and blast, it is a nasty spewing beast, and the 9mm loads are much more friendly.
The 9mm 124 grain loadings struck an excellent balance between power and controllability, and both hit to the sights (vertically) in the 547. Like the mid-range (aka, low recoil) .357 loads, they are a near perfect loading for a 3” K frame carry gun.
I have shot the 547 enough to get a good feel for it. Ignition has been 100% with all ammunition fired. It has been reliable with 115 grain factory FMJ from various makers, NATO-spec 124 FMJ, commercial hollowpoints from the big manufacturers and smaller shops like Doubletap and Corbon, and cast bullet handloads that I have loaded for it. That reliability comes at a price with the 547, as the heavy trigger is harder to manage than comparable S&W K frames. I find that if I relax my grip even a little, and do not completely focus on my trigger press, shots will drift left.
Comparing the strain screw from a standard K frame round butt to the 547’s reveals it is indeed noticeably shorter. Out of curiosity, I installed the standard K screw into the 547 and the trigger pull became . . . instantly delicious. I have not had a chance to shoot it yet, so altered, but I’m hoping it has enough “oomph” to bust commercial primers reliably. If the longer screw was strictly used to ignite Egyptian surplus submachinegun ammo, and the normal one will do the job with regular ammo, it will greatly improve the “shootability” of this gun!
Extraction of empties was also flawless with the 547. I treated it like any other revolver, primarily using the “universal” method– striking the extractor rod with my right palm. I occasionally used my left thumb to press the rod a la the FBI method. I never had to strike it twice.
Reloading the gun was a little weird. HKS actually made a speedloader for the 547 (I would wager that they are the most uncommon HKS loader out there). The stubby 9mm rounds handle differently than long, skinny rounds like .357 Magnums. The first several times I tried to load with the HKS, I would bumble it, and lose at least one round. I found that using the center pin of the loader to push down on the extractor before twisting the knob gave better results. It seemed to set the extractor and allow the rimless rounds to fully seat in the chambers. If I tried to hurry the process, the loader would pinch a round and carry it with the loader as it was discarded.
The key to loading the 547 was using deliberate movements. Rounds would occasionally not fully seat even when I did everything right. These would have to be pushed in with a fingertip before the cylinder could close. The 547 would hugely benefit from a spring-assisted loader like an SL Variant or a JetLoader. Tuff Products’ .32 caliber Quick Strips also fit 9mm rounds, and work really well with the 547. You can maintain pressure on the cartridge heads as you peel the strip off, and keep them in the charge holes. They were more reliable than the speedloader at getting six new ones in every time. The strips would be mandatory kit if you chose to carry this gun.
Missing in action
The 547 had a short production run from 1980-1985. Reportedly, only 10,270 guns were made, with 6,486 of them being 3” variants. The gun had one engineering change in 1982; The pinned barrel was deleted, and the three letter/four number serial number format was adopted at AAF—-. Internet rumors claim the 547 was S&W’s most expensive revolver to produce.
Maybe some of you readers have a better idea as to why it went away so soon? If so, please share, because decades later, this revolver still seems cutting edge!