Ruger GP100 .357 Magnum Revolver

By the Guns and Shooting Online Staff

Ruger GP100
Illustration courtesy of Sturn, Ruger &Co.

Back in the days when Colt and Smith & Wesson revolvers dominated the U.S. police market, William B. Ruger, co-founder and CEO of Sturm, Ruger & Company and one of the most accomplished gun designers in American history, wanted a piece of the action. His .22 autoloading pistol was the best selling gun of its type, as were his single action rimfire (Single Six) and centerfire (Blackhawk) revolvers.

In 1972, Bill Ruger introduced his "Six Series" DA revolvers, first the Security Six (fully adjustable sights, square butt) and then in quick secession the Service Six (fixed sights, square butt) and Speed Six (fixed sights, round butt). Like his previous SA revolvers, the new DA models were built around investment cast "medium" size frames, used music wire (coil) springs throughout for enhanced reliability and a transfer bar to ensure safety against accidental discharge. They were reliable, well made and affordable. Aimed straight at the police, military and civilian self defense markets, these were six shot, .38 Special and .357 Magnum (later 9x19mm and .38 S&W, swing out cylinder, hand ejector, police service style revolvers. Colt and Smith & Wesson were forced to recognize that there was a serious new player in the service revolver market.

Over 1,500,000 Six Series revolvers had been sold by the time the line was discontinued in 1988. The replacement for the Six Series was the GP100, introduced in 1985 and the subject of this review. If the Six Series can be equated to the S&W "K" frame line, the GP-100 can be equated to the S&W "L" frame line. It is built on a larger, heavier frame designed specifically for the .357 Magnum cartridge.

Colt's Python, introduced in 1954, had showed the world what an ideal .357 Magnum DA revolver looked like. The Python was built on a .41 caliber frame, not a .38 Special (.35 caliber) frame, for extended use with .357 Magnum cartridges. Medium frame revolvers, such as the S&W K-series and Ruger Six Series, developed problems if fed an extensive diet of full power .357 Magnum cartridges. They were strong enough to contain magnum pressures, but wear was accelerated. A Python size revolver was the answer. S&W merely copied the Python silhouette, full length barrel lug and all, inserting inferior S&W lock work, but Ruger took the opportunity to further improve his DA revolvers.

The GP100 uses a larger frame than the Six Series and incorporates some major improvements. First is the cylinder locking system, which is latched to the frame at the crane, as well as at the back of the ejector rod. Ruger calls this a "triple lock" cylinder, but it really isn't. The purpose of the bolt at the bottom of the cylinder (which Ruger advertising counts as a cylinder lock) is to prevent cylinder rotation, not keep the cylinder in the frame. Unlike the cylinder latches, the bolt retracts when the cylinder turns.

Another improvement is a stub (half size) grip frame that replaces the conventional grip frame, allowing the attachment of a one-piece grip of practically any size, shape or style. Grip panels don't attach to the sides of the GP100's grip frame, as with traditional revolvers. Instead, a one-piece grip slides over it and is attached by a screw through the bottom of the grip.

Like the Six Series, but unlike Colt and S&W revolvers, music wire springs are used exclusively. The investment cast frame has no removable side plate; most of the internal parts are attached to the trigger guard assembly, which is removed from the bottom of the frame. The by now familiar Ruger transfer bar ignition system, which makes carrying a revolver with a fully loaded cylinder absolutely safe until the trigger is intentionally pulled, was retained. To swing out the cylinder, press in on the button mounted in the frame's left recoil shield.

GP100 revolvers are offered in alloy steel with blued finish or in stainless steel with satin finish, with adjustable or fixed sights, with or without full length barrel lugs and with various grip styles. The usual barrel lengths are 3", 4.2" and 6", although other barrel lengths have been produced as distributor specials. The GP100 was designed as a six shot, 357 Magnum (also accepts .38 Special) service revolver and .357 remains the most popular caliber. Recently, a seven shot version in .327 Federal Magnum has been offered. For this review, we requested a .357 Mag./.38 Special GP100 in stainless steel with a 4.2" barrel from the good folks at Ruger.

GP100 Features

  • Recoil reducing black rubber Hogue Monogrip
  • Triple locking cylinder (See comments above)
  • Patented grip frame accommodates a wide range of grips
  • Easy takedown of integrated subassemblies requires no special tools
  • Patented Ruger transfer bar ignition system
  • Heavy, precision rifled barrel
  • Fully adjustable Patridge type sights
  • Included hard plastic case

Specifications (as tested)

  • Catalog number: KGP-141
  • Model number: 1705
  • Caliber: .357 Magnum (also .38 Special)
  • Capacity: 6
  • Material: Stainless steel; satin finish
  • Trigger pull: 4.5 lbs. SA, 12.8 lbs. DA
  • Front sight: Ramp
  • Rear sight: Fully adjustable
  • Barrel length: 4.2"
  • Twist: 1:18.75"
  • Overall length: 9.7"
  • Weight: 40 ounces (empty)
  • 2013 MSRP: $759

The actual bullet diameter of both the .38 Special and .357 Magnum revolver cartridges is .357" and, because the .357 Magnum is based on a lengthened .38 Special case, any .357 revolver can also fire all .38 Special ammo. Standard velocity .38 Special cartridges make excellent practice or match ammo for any .357 revolver and .38 Special +P ammo is a viable choice for personal or home defense encounters anticipated to occur indoors or in dim light, where the muzzle blast of a full power .357 Magnum cartridge is literally deafening and the flash is blinding. Outdoors in good light, the full power .357 Magnum really comes into its own as the premier self-defense handgun cartridge, as it has the highest one shot stop percentage of any handgun caliber. With heavy for caliber bullets, it is one of the few handgun cartridges adequate for defense against large predators in the field.

Our new GP100 was supplied in a handy plastic carrying case. Inside were the usual accessories, including a gun lock and an instruction manual so larded with safety warning interruptions as to be almost unintelligible.

Initial inspection of our test gun revealed that the fit and finish were generally good. Ruger's satin stainless steel external polish is one of the most attractive. It is not mirror reflective like a Vaquero high polish or nickel plating, but it's finer than many manufacturers' matte stainless finish. The top of the barrel rib is grooved to help break-up reflections. The fit of the trigger guard assembly to the frame was excellent, with the join line almost invisible. The fit of the cylinder crane to the frame was only satisfactory, with a small gap where the two meet. The slot in the barrel's under lug for the ejector rod is rather crudely cut, both longer and wider than necessary with a pointless cut-out at the front. The ejector rod itself is perfectly straight, without any visible wobble when the cylinder is spun.

"Read Instruction Manual" is stamped into the left side of the barrel above "-Ruger-" and "Newport, NH USA" in small print. "Ruger GP100" in much larger letters appears to have been laser etched into the right side of the barrel, with "357 Magnum" on the under lug below. The serial number is stamped into the right side of the frame below the cylinder, along with the traditional Ruger eagle in a circle emblem.

The entire barrel has a rather amorphous shape, with the top rib and full length bottom lug sort of melting into the barrel, rather than being clearly defined. Look at a Colt Python to see how it should be done. The oval trigger guard, on the other hand, is nicely shaped and adequately spacious. The frame's recoil shield complements the lines of the gun. The shape of the supplied Hogue Monogrip leaves a lot to be desired, functionally and aesthetically. (More on function a bit later.) Aesthetically, its shape is just plain ugly and it detracts from the lines of the revolver. Considering that the GP100's stub grip frame allows a great deal of freedom in grip shape and the earlier Ruger Six Series and Redhawk DA revolvers had much more pleasing grip shapes, the ugly Hogue design chosen for the GP100 is a bit of a mystery, when it would be so easy to correct.

The barrel is a useful place to add weight for stability when shooting offhand, particularly with a 4" barrel. Our test revolver has a full length barrel under lug and a solid top rib. The ramp front sight is pinned to the top rib. The front of the under lug slants back from the muzzle and its body is given a semi-rectangular cross-section, which is much less attractive to our eyes than the seminal Colt Python's round under lug. Regardless, the GP100 has a solid feel and we know it is an unusually strong DA revolver. At 40 ounces with a 4.2" barrel, the GP100 is obviously not a lightweight.

Out of the box the GP100's single action trigger pull measured 4.5 pounds with only a little take-up in two perceptible stages. The double action pull measured 12.8 pounds.

As usual, we conducted our test shooting at the Izaak Walton outdoor range south of Eugene, Oregon. This facility has covered shooting benches and 25 yard target frames convenient for pistol testing. Chuck Hawks, Rocky Hays and Jim Fleck, all G&S Online staff members, participated in the shooting. The weather was typical of April in Western Oregon, with partly sunny skies and a high temperature in the 60's F. The wind was gusting to about 10-15 MPH, but not much of a factor for 25 yard pistol shooting with a .357 revolver.

For the shooting part of this review, we used one standard velocity .38 Special, one .38 Special +P and two .357 Magnum factory loads. These were the Winchester/USA .357 Mag. 110 grain JHP (MV 1295 fps), Remington/UMC .357 Mag. 125 grain JSP (MV 1450 fps), Remington/UMC .38 Spec. +P 125 grain SJHP (MV 945 fps) and Winchester/USA .38 Spec. 125 grain JSP (MV 850 fps). Due to the ammunition shortage caused by the Obama post reelection gun ban effort, to conserve ammo we fired three shot (instead of our usual five shot) groups at bullseye targets from a Pistol Perch rest.

25 Yard Shooting Results

  • Winchester/USA .357 Mag. 110 grain JHP: Smallest group = 1-1/8"; Largest group = 3-1/4"; Mean average group size = 2.33"
  • Remington/UMC .357 Mag. 125 grain JSP: Smallest group = 1-3/4"; Largest group = 2-3/4"; Mean average group size = 2.29"
  • Remington/UMC .38 Spec. +P 125 grain JHP: Smallest group = 1-1/2"; Largest group = 2.0"; Mean average group size = 1.83"
  • Winchester/USA .38 Spec. 125 grain JSP: Smallest group = 1/2"; Largest group = 3-5/8"; Mean average group size = 2.13"


This time out, Rocky shot the smallest recorded group. Overall, the accuracy was about what we expected from a new, 4" barreled service revolver shooting economical factory loads. It is a definite cut above the typical service autoloader, but not the equal of a target revolver. The GP100's excellent, fully adjustable, Patridge type sights made zeroing the gun quick and easy.

Ruger revolvers are renowned for their strength, durability and reliability. The GP100 reviewed here was typical, as there were no malfunctions of any kind during our test shooting.

Our experienced shooters considered the recoil of the GP100 manageable with full power .357 loads, although the 125 grain Remington magnums did sting our hands, mostly due to the deficiencies of the Hogue Monogrip. Like all magnum handgun cartridges, the .357 really deserves at least a 6" barrel to maximize performance and control muzzle blast. Full power .357 loads are not a good choice for inexperienced shooters, who are likely to quickly develop an accuracy destroying flinch. Fortunately, the GP100 is far more pleasant to shoot with all .38 Special loads, including +P ammo. Hitting with a .38 is far better than flinching with a .357, whether practicing at the range or shooting to save your life.

The supplied Hogue Monogrip drew a lot of criticism from our shooters. Chuck complained that the spacing and angle of the very pronounced finger grooves did not match his hand. (Finger grooves only work properly when they are custom fitted to an individual hand.) Rocky disliked the grip's pronounced vertical rise at the top rear (where it meets the thumb web of the shooting hand). No one liked the grip's overall shape or its pronounced hump in the middle of the backstrap. Its shape is too narrow from side to side and too long from front to back, making for a long reach to the trigger. The lack of width across the back strap amplifies the effect of recoil and the rubber compound is too hard to help much. The molded stippling, used instead of checkering, succeeds only in making the grip look like it is covered with tiny warts. In any case, the Monogrip has an ugly shape that does nothing for the GP100's lines. A Pachmayr Presentation grip would be a big improvement.

The GP100 is similar in size to a Colt Python or S&W 686. It fit nicely in an Uncle Mike's Sidekick Size 2 nylon hip holster originally purchased for a Colt Python revolver with a 4" barrel.


We took the liberty of making some simple modifications to our test GP100 after the shooting portion of this review with the idea of making it an ideal home defense handgun. Revolvers are inherently superior home defense guns, as (unlike autoloading pistols) they can remain fully loaded and ready to go for years without deteriorating, because all springs are relaxed. In an emergency, there are no safeties to manipulate or fumble; just grab the revolver and pull the trigger to fire when needed.

We replaced the stock Hogue Monogrip with a Crimson Trace Lasergrip #LG-344. (A review of the LG-344 can be found on the Handgun Information page.) This square butt, black rubber grip incorporates a red laser that projects an aiming dot just under the cylinder, along the lower right side of the barrel. The grip has much more restrained finger grooves than the stock Monogrip, allowing more flexibility in shooting hand grip and a better feel.

The laser aiming point is adjustable in windage and elevation by means of tiny screws in the top and side of the diode housing via the supplied hex wrench. A single CR123 lithium battery provides approximately 20 hours of continuous laser life, amounting to about a year of normal service.

The laser activation button is located at the front of the grip below the trigger guard, where the middle finger of the shooting hand naturally falls. It is a momentary switch, meaning that the laser is only on when the activating button is held in. This takes little finger pressure and, essentially, the laser is on any time the revolver is gripped normally. There is also a very small master on/off switch recessed into the bottom of the grip. This master switch allows the laser to be deactivated, useful for conserving battery life when shooting in normal daylight conditions.

Crimson Trace uses the maximum laser output allowed by law, a class 3R (5mw peak, 620-670nm) visible laser diode. At night or in very dim light, the laser dot is visible for hundreds of yards. In daylight, the red laser dot is visible at 15-25 feet. In my home at night, with all the room lights on, the red dot is very bright at the maximum distance available, approximately 50 feet. The laser beam itself is invisible, so an armed opponent to the side cannot see it to pinpoint your location in the dark.

Crimson Trace recommends zeroing the laser at 50 feet. At any distance from the muzzle to 50 feet the point of impact is within 1.25" of the point of aim (on our GP100) and the laser dot is " in diameter. The Lasergrip does not interfere with holstering the revolver and a special holster is not necessary to accommodate a Lasergrip equipped GP100. Crimson Trace Lasergrips are made in the USA and come with a three year materials and workmanship warranty. The 2013 MSRP for the LG-344 is $299 direct from Crimson Trace (

Next, we replaced the stock sights with XS Sight Systems Big Dot Tritium front and Express white line rear sights. This is feasible because the GP100's front sight blade is retained in its slot in the barrel rib by a pin that allows removal. The XS Express rear sight blade simply replaces the stock Patridge sight blade. The Tritium front bead glows in the dark, allowing a quick "flash" front sight acquisition for close range defense. The GP100 is one of the few revolvers for which tritium night sights are available. In daylight, the correct express sight picture is with the front bead centered on the middle of the rear sight's shallow "V." The bullet should impact at the top of the front bead at the chosen distance, which in our case was 25 yards. The 2013 MSRP for the Big Dot Tritium Express set is $90, direct from XS Sight Systems (

From a bench rest at 25 yards, the Express rear and Big Dot front sights are less precise than the very good Patridge sights supplied with the GP100. However, in a dark house late at night the XS Big Dot tritium front sight is much more visible than the stock black ramp; The Express sights are accurate enough to stop a threat at indoor ranges. So is the Crimson trace Lasergrip. With both on the same revolver, the shooter has a choice of dim light aiming systems viable to 50 feet or more.

Finally, a Wolff Shooter's Pak (2013 MSRP $10.50) reduced strength spring kit was ordered for our GP100 to replace the stock hammer and trigger return springs. We used the Wolff nine pound hammer spring and eight pound trigger return springs (the lightest weights supplied) in our test gun. This noticeably lightened the hammer draw and both the DA and SA trigger pulls without degrading ignition reliability. The SA pull was reduced to 3.5 pounds. Wolff Gunsprings can be ordered direct online at

We are pleased with our drop-in modifications. We think the result is, as we hoped, an ideal home defense handgun.


Because we dislike the indoor muzzle blast of .357 Magnum cartridges and their blinding flash at night, we choose to use .38 Special +P cartridges for home defense. For the GP100, we chose the Federal Premium Personal Defense 129 grain Hydra-Shok JHP load.

The .357 Magnum Ruger GP100 is a good choice for urban or suburban home defense. It also has potential for protection in the field when loaded with full power .357 Magnum loads using heavy for caliber (158-180 grain) bullets. Overall, the GP100 is probably the best mass produced .38 /.357 DA service revolver on the market today.

Note: A review of the Ruger GP100 in .327 Federal Magnum caliber can be found on the Product Reviews page.

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