The 10mm Auto is one of those cartridges with the capacity to capture the imagination like few others. Daydreams of charging feral pigs, scarcely trod trails, and pine-perfumed air are nearly inescapable when handling a 10mm. I fell under this spell years ago, and managed to break free for awhile…until the 10mm GP100 came along. The Centimeter GP was a pleasant surprise; I had given up hope of owning a duty-sized wheelgun in BESTmm. Handling and shooting this versatile revolver stokes a handgunner’s imagination like few other revolvers and suffice to say, I am a fan. This field report will explain why.
The most important criteria in a handgun intended for any purpose other than pure entertainment is reliability. A hunting or defense sidearm must be reliable above all else. I tested the 10mm GP100 with over a dozen different loadings from over half a dozen manufacturers including Double Tap, Federal, Georgia Arms, Remington, Sig Sauer, Speer, and Underwood. These spanned the power spectrum from middling .40 S&W levels to rip-roarin’ 10mm stuff that would warm the heart (and hands) of The Colonel himself. I shot FMJs, JHPs, bare, hard-cast lead, and some other oddball stuff.
In total I fired somewhere north of 600 rounds through the gun with zero maintenance of any kind. When shooting 10mm ammunition I experienced not a single malfunction of any type, which is to mostly be expected with a new revolver. I assess this gun as extremely reliable with proper ammunition.
During my entire time with the 10mm GP100 I attempted to get .40 S&W cartridges to work reliably. As of now I have been unable to make this a reality. Thanks to Tom at TK Custom we are almost there, but not quite. My thoughts on the matter are this: shooting the .40 S&W in this gun is neat, and makes it a bit more flexible. However, this handgun is designated as “10MM AUTO” and NOT a “10mm/.40S&W” as some articles claim. If we can make .40 S&W work in it, that’s cool, but you probably shouldn’t purchase one with the primary goal of shooting a cartridge for which it isn’t intended, much like you shouldn’t buy a 9mm in hopes of shooting .380 ACP.
The 10mm is renowned for its velocity potential. One thing I (and surely others) was curious about was velocity from the GP100’s 4.2″ barrel. In addition to wearing a (theoretically) shorter barrel than many autoloaders, the GP100 also has the infamous cylinder gap (and quite a bit of free-bore) that one naturally assumes robs a bit of velocity. Further complicating matters, manufacturers’ advertised velocities are just that: advertised. There is often a difference between “advertised” and “actual.” With that in mind I decided to test the 10mm GP100 alongside a more traditional platform for the 10mm cartridge: a SR1911 in 10mm that Ruger was also kind enough to loan us.
I loaded up seven different rounds from four different manufacturers and headed to the range. I was somewhat surprised at two findings. First, every single loading tested clocked in below advertised velocities, and sometimes well below. This was not unique to one gun or the other – in both platforms all ammunition tested failed to reach advertised velocities. Secondly, the difference between the revolver and the 5″ semi-auto weren’t as great as I would have imagined. The revolver held its own, staying neck-and-neck with the longer automatic. In one case the revolver even bested the 1911 in the velocity department.
The velocities listed in the chart below are an average of five shots.
|Underwood 100-gr Xtreme Defender||1778||1769||-9 FPS|
|Sig 180-gr. V-Crown JHP||1192||1171||-21 FPS|
|Sig 180-gr. FMJ||1198||1192||-6 FPS|
|GA Arms 180-gr. Bonded Defense||1153||1120||-33 FPS|
|DT 200-gr Controlled Expansion||1108||1111||+3 FPS|
|Double Tap 200-gr. FMJ Match||1079||1059||-20 FPS|
|Double Tap 230-gr. WFNGC||1085||1063||-22 FPS|
|Average (Mean):||1228||1212||-15 FPS|
My takeaway from this is that one should worry less about the revolver’s cylinder gap, and more about the ammunition he or she is shooting. The Georgia Arms 180-grain load exhibited the biggest difference (33 FPS), but this was also the load with the biggest extreme spread (35 FPS in the SR1911, 40 FPS in the GP100). Even factoring that in, the mean velocity loss from the revolver was only 15 feet per second.
The bigger difference exhibited was the difference between manufacturer’s stated velocities and actual velocities. I’m not finger-pointing; testing velocity in a Glock may well result in better results than a traditionally-rifled barrel. The point is, don’t believe everything you read on a box or website. If you are relying on a certain load to meet an energy requirement, you should probably test the ammunition yourself.
There are quite a few factory 10mm loads I didn’t shoot. My velocity test conspicuously lacks anything in the intermediate weights (135- to 165-grain). Since the single Underwood load I tested was also the most consistent, I’d like to look at more of their offerings, as well. I plan to continue testing 10mm velocities in this revolver and may eventually run a more detailed article on the topic.
Recoil in the 10mm gp100
Of course there is no such thing as a free lunch, and for every action there is an equal and opposite reaction. Heavy bullets thrown at high velocities inevitably generate recoil. Recoil is also one of those “squishy” factors that is very difficult to quantify or explain with any measure of objectivity. Instead we’re limited to subjective words like “tolerable,” “stout,” or “punishing.” Sadly, this review will be little different in that regard, but I did find something interesting with the 10mm GP100.
In my initial review of this revolver I didn’t dwell on recoil because, to be honest, I didn’t notice it. I chalked this up to one of several things. It has been a while since I’ve owned a 10mm, so maybe I just forgot the nature of the recoil. Maybe I had grown more experienced and seasoned as a shooter in the interim, and recoil didn’t affect me as much. Or it could be the case that the 10mm’s recoil, like many other legends about the cartridge, had been greatly exaggerated. Turns out, none of these was the case. This became obvious when shooting the SR1911 with “real” 10mm ammo.
I had shot the GP100 with a wide array of ammo: low-powered, high-powered, fast, slow, light, and heavy. Some exhibited stronger recoil than others, but none were unpleasant in the slightest. Upon firing the first round of a magazine of 230-grain WFNGCs from Double Tap through the SR1911 I was taken aback. “So this is the unmanageable recoil they all talk about!” Firing the full magazine became a chore, as were a couple other loads, like Underwood’s 200-grain XTP. Despite being three ounces lighter than the SR1911 (37 ounces vs. 40 ounces) recoil in the 10mm GP100 is much tamer. This gun is an all-day-shooter with anything you care to load into it.
I’m not quite sure what to make of this, or to what to attribute it. Maybe it’s the unique shape and/or angle of the Match Champion’s grip? Perhaps the mass of the slide moving rearward at such high speed adds some additional energy to the SR1911s recoil cycle. It is possible that enough pressure is lost through the revolver’s cylinder gap that recoil is actually lessened, but the velocities recorded above would seem to contraindicate this theory. My pet theory is that maybe – just maybe – the “10MM AUTO” is a revolver cartridge that was switched at birth and should have been properly designated “10MM REVO”. . .
In my initial review of the 10mm GP100 I promised some bench-rested groups. I am going to let you down in this one because of three things. First, I find that I am neither terribly interested in, nor have the patience for, shooting from the bench. Secondly, while nitpicking such groups provided by other outlets is entertaining (I do it, too), it’s not how this gun will be used by me, or probably, by you. Finally, I found that I am not very good at generating minuscule groups from the bench. When shooting in single action from the bench my groups actually seemed to open up slightly, so that is a human problem I’m going to have to work on.
So instead, I tested the accuracy of the GP100 thusly: I fired a full cylinder of six shots from the offhand (standing) position, in double-action, at a distance of 25 yards. Each group was fired at a NRA 25-yard Slow Fire Pistol target. I believe the 5 5/16ths-inch black circle in this target as sufficiently small to represent a headshot on a human aggressor, or a humane, killing shot on medium/large game. I list the size of each group, as measured from center-to-center of the two most distant shots, in the captions.
For this test I chose four loads from four manufacturers. Two of them represent excellent defensive cartridges for this caliber. They are premium, jacketed hollowpoints from well-known manufacturers: the new 200-grain Speer Gold Dot and the relatively new 180-grain Sig V-Crown. Both of these loads turned in respectable groups. Both also grouped slightly low because of sight regulation at the time of testing.
The other two represent potential outdoor loads more suited to hunting or predator defense, the other major use-category for the 10mm wheelgun: Underwood’s loading of the 200-grain Hornady XTP, and Double Tap Ammo’s 230-grain WFNGC hard cast bullet. Both of these printed closer to center, though groups opened up ever so slightly.
I’m sure my results here are nothing to write home about, especially in comparison with sub-2″ groups that are common to read about. But, they are honest, real-world-condition groups at a decent distance and I am satisfied with them.
Of note, there is some POI shift depending on the load used. Mostly this isn’t too drastic, and it is probably possible to find suitable hunting and defensive loads that share a point of impact. The extremely light, fast 10mm bullets don’t abide this rule, however. The 100-grain Underwood load printed several inches below the POA that worked reasonably well for all other loads tested. I will test some loads in the future and get some better data on how severe the difference between POI is.
Odds ‘N Ends
One thing that bothered me about the .357 GP100 Match Champion was the propensity of the rear-sight pin to walk out. Losing the rear sight for want of a pin is a serious fail. The older friction-fit pin has been replaced with a roll pin in this variation of the GP100, and for the better. Through over 600 rounds (so far) of 10mm ammunition, the pin has kept itself firmly in place. I am extremely impressed with this development.
Speaking of sights, I also reached out to Hamilton Bowen to request a Rough Country Rear Sight for the 10mm GP100. Make no mistake: the OEM rear sights on the Ruger support excellent accuracy. However, as my new “for-all-reasons” revolver, I feel the GP100 could us a sight upgrade to the absolute best-in-class. Which leaves me with the front sight. I am at a loss for what to do with it. The fiber optic isn’t bad, and it’s certainly better than the version on the .357 Match Champion. But personal preference being what it is, I don’t like it. At some point I may have a gold-bead front manufactured for this revolver if I can’t find a suitable aftermarket production sight.
The provided moon clips from Ruger work well and will definitely get you started with this gun. They are easy to load and unload without tools, and support extraction of fired cases. However, I am sold on TK Custom clips. They hold the cartridges more securely and prevent the “drooping” that is common with the Ruger clips. They can’t be easily loaded by hand, but if you’re planning to shoot this gun a lot they are well worth the investment.
I also fired this gun quite a lot without moon clips to no ill effect. Since the cartridges headspace from the case mouth, moon clips aren’t strictly necessary. This is a nice touch as the loss, damage, or simple forgetting of moon clips doesn’t render your revolver inoperable. Because the cases sit so high in the cylinder, they are easily plucked out by hand. I also found a 10mm 1911 magazine to be an ideal cylinder loader. If one wanted to carry the 10mm GP100 for defense but not a spare moon clip, he or she could keep the rounds in the gun in a clip for fast ejection, and the spare rounds in a 1911 or Glock 20 magazine. This isn’t the fastest reload, but it’s far superior to reloading loose rounds.
My Ammunition Choices
Like me, but unlike some revolvers, this gun is a generalist. It will work pretty well for just about any purpose you’d expect from a duty-sized revolver. I essentially see the 10mm GP100 as ideally suited to three purposes: self-defense against human aggressors, animal defense, and hunting. My selection of ammunition reflects these varied use-cases. The intersection of recoil, accuracy, and terminal effectiveness will guide my personal choices for ammunition in the 10mm GP100.
For personal defense purposes I currently have some Sig 180-grain V-Crown JHP and some of the brand new 200-grain Speer Gold Dot. Both of these mid-range rounds exhibit manageable recoil, decent accuracy, and performed extremely well in Lucky Gunner’s recent 10mm gel test. Both of these would also doubtlessly perform well on light game like whitetail, which I hope I have the chance to test this year. I tend to favor the Gold Dot. It’s slower velocity means its point of impact is likely closer to that of heavy loads, allowing me to regulate sights at a single point of impact or acceptable middle-distance.
For for predator defense, and should I ever dip my toe into heavy or dangerous game, I’ll stick with hard cast, wide flat nose bullet like those offered from Buffalo Bore, Double Tap, and Underwood. Further testing is required to determine which of these I prefer. Double Tap’s 230-grain load prints reasonably close to the Gold Dot’s point of impact, but I’m going to test a few more anyway. I would also love to find a practice load that shares a point-of-impact with the more “serious” ammo.
The Bottom line
I am smitten with this revolver – it is truly a dream come true. I would have been happy with just about ANY 10mm revolver, but the 10mm GP100 Match Champion is really something special. Expect to see this revolver on these pages a lot more in the coming months. I am still a huge fan of the .357 Magnum and the revolvers that chamber it. But. . . if you want something a little off the beaten track, something just a little different, and something that packs a lot more punch, the 10mm GP100 should be on your short list. This revolver is a shooter, a hunter, a defender, all in a duty-sized package. However. . .
There will be a Part III to this review. I thought I had written just about everything that needed to be written about this revolver until yesterday. I took the 10mm GP100 to the range and fired a final 100 rounds, and discovered a couple new things. Apparently this revolver hasn’t given me all of its secrets yet. I will write these up, along with some more velocity data, and some point-of-aim/point-of-impact information about the 10mm GP100. Stay tuned!