Cosaint COS11 Review

Sometimes, you’re seized by the desire for something a little novel. I had been investing heavily in BUL 2011s (and loving them), and wanted a similar sort of gun for shooting USPSA Single-Stack and IDPA CDP. Of course, USPSA Single-Stack only allows single stack 1911 magazines, so this limits your choices a bit. I initially went looking for a Staccato R in .45 Auto; when this didn’t pan out, I found a different option: the Cosaint COS11, which is very similar in many ways.

Cost: $1600, which I paid in full (no discounts!).

Caliber: .45 Auto

Included in the box: The gun, two Wilson Combat 8rd magazines, a branded pistol case, and some various literature/stickers. The case is a Plano Protector pistol case. I’d say it’s about in line with what you’d expect for the money.

Magazine Type and Capacity: Standard single-stack 1911 magazines, 8rd capacity.

Platform Background: Sandy Strayer and Virgil Tripp designed the modular 2011 platform in the 1991-1994 time frame, and were responsible for the very well-known companies of STI (now Staccato) and SVI (along with Michael Voight; now Infinity). The patents on the 2011 have long expired, and now other companies like BUL, Atlas, Limcat, Springfield Armory, and others offer 2011-style guns (2011 is a trademark of Staccato).

What sets a 2011 apart from a double-stack 1911 (as made by RIA, Para, etc.) is the modular frame. The frame contains the slide rails, the dust cover (or accessory rail), and the serial number, as well as the pins for the fire control group and safety. It also has bushings for the grip module (which is typically steel or polymer). While not quite as self-contained as something like the Sig FCU, it was still a huge leap forward for the 1911 platform, and gave it a degree of modularity and flexibility not seen before.

Nearly all 2011s are double-stack guns; the few exceptions are the Staccato C (not C2), the Staccato R, the CWA custom rimfire pistols, and the gun we’re looking at today, the Cosaint COS11. The obvious question, of course, is why bother? You can get a quality single-stack 1911 at a somewhat lower cost.

The answer is simple: a slightly lighter gun with a double-stack-sized polymer grip is going to shoot better for some people. My sweet spot is somewhere in the 33-43oz range. Glocks are much too light; steel-grip 2011s are just a bit too heavy. Guns like my SAS II are in that Goldilocks “just right” zone that feel great while shooting. While it is certainly tempting to focus entirely on heavy weight for recoil mitigation, mitigating recoil is not the only thing you do with a gun… you transition, you draw, you reload. All of those things are just a little easier with a lighter gun.

Cosaint (pronounced “cho-sent”) entered the market in the 2020 with their COS11 modular single-stack offering. They expanded to double-stacks (“COS21”) in 2021. They’re owned and run by Greg Mooney, who was president of STI from 2014 until they got bought out and turned into Staccato. Greg thus knows a few things about building 2011s, and seems to be building some fine guns at a reasonable price.

Cosaint’s 2011s fall into what I’d call “semi-custom” category. There does not seem to be a ton of hand-fitting and trigger tweaking involved (past the minimum required), but you can specify exactly what spec gun you want and get it in a reasonable time frame.

Aesthetics, Feel, and Specs: The COS11 is a modular pistol, and it can be built in a variety of ways. The one I purchased is attractive-looking, and has a polymer grip with square trigger guard and right-handed grip panels (made of G10) on it for further customization. There’s also an option for a pure polymer stippled grip option, which is maybe a little uglier, but probably works just as well.

The commander-length slide is standard 1911 fare, with a flush-cut bull barrel, respectable sights (adjustable two dot rear, fiber optic front), and front slide serrations. The steel frame has a “tactical” accessory rail. Slide to frame fit is very tight; no wiggles here. In fact, some of the color on the rails was coming off, so it probably will get even smoother with some more use. When I weighed the gun, it was about 32.5oz without magazine, which is about what a steel-framed 2011 typically weighs.

Oddly enough, when I measured the barrel using a rod, it was 105mm (~4.15″) and not 4.25″. This might have been a measuring error on my part, so I reached out to the manufacturer to confirm. They told me they cut the barrels flush to the slide, so my measurements may well have been correct. While this may seem like a tiny difference – and it is – the implications for usage in USPSA are pretty substantial since, in Single Stack division, bull barrels can be only used in guns with a barrel less than 4.2″.

Trigger pull weight was about 4.25lbs, which is heavier than the manufacturer specified 3.5lbs. This was disappointing in a $1600 pistol – I’ve had 2011s not far off in price come with 3.0lb triggers – but I could see how it makes sense in a gun marketed for defensive use. Pre-travel and over-travel were minimal, though, so the trigger at least felt snappy at speed.

The stippling on the gun looks hand-done and is definitely on the better end of such things. The front and back of the grip are both stippled, as is the front of the trigger guard. You’ll notice there is a small gap between the grip safety and the frame on each side; this isn’t very attractive, but I didn’t notice it when shooting the gun.

Controls: All controls are 1911 standard.

Holster Compatibility (out of the box): I was told by the manufacturer that they recommend Staccato C holsters. For what it’s worth, my Ghost BUL M-5 holster fit it just fine.

Accessory and Sighting Mounting Options: The COS11 I purchased is not cut for optics; this is OK, since I planned on using it in IDPA CDP (and USPSA Single-Stack) division, which is irons-only.

It also has an accessory rail; again, I’m not sure I’d put a light on this gun for my intended usage, but if I wanted to (for a low-light match, perhaps?), the option is there.

I tried putting my 22lr GSG conversion slide on the gun; it physically fit, but got hung up on something during cycling (maybe the disconnector). The CWA 22lr slide functioned somewhat, but seemed to lock up randomly. I would not recommend this gun out of the box for usage with 22lr, but I suspect it is possible to make it work with some gunsmithing on the disconnector.

Testing: I tested the COS11 using my own personal reloads. This is not the hottest ammo in the world, but it has never had issues cycling any of my guns in the past. I also ran half a box of Speer 230gr GDHPs through it to test for feeding hollow-points (frequently a problem in 1911s).

My testing is mostly focused on reliability and perceived shooting characteristics (recoil, trigger feel, ergonomics, etc.); it’s an unusual modern pistol that will not perform with adequate practical accuracy. I did not make any modifications to the gun besides spraying the rails with some CLP. I also used 10rd Wilson Combat magazines for portions of the testing to further explore magazine compatibility.

Initial testing, conducted indoors at the NRA HQ range, was rather boring, in a good way. The sights were about an inch to the left at 7yds, which was easily corrected via adjustment. Feeding, firing, extraction, and ejection were flawless across magazines and ammo types. All controls worked well, albeit the gun exhibited a tendency to drop the slide when forcefully inserting a new magazine, and the magazine release was “sticky” and would sometimes hang up slightly before moving as expected. I attempted to pull out the magazine release and smooth the channel a bit, but the screw wouldn’t move easily at the time, so I decided to leave it for another day.

Accuracy was also as expected and produced one ragged hole when I did my part. Oddly, I found that the gun seemed to shoot much tighter groups at 10yds with 4.5gr of Bullseye powder than it did with 5.7gr of Unique. I felt that the sights would have been better if the rear sight dots had been blacked out, but I initially refrained from doing this in the interest of giving the factory gun a fair shot. A lighter trigger would probably have tightened the groups up a bit, but this is probably nitpicking for practical accuracy at purposes.

Recoil was mild, and keeping a grip on the gun was easy due to the stippling and well-designed frame. You’d never confuse this gun in .45 Auto with a 9mm, but it was a very pleasant shooter. However, keep in mind that the other guns I shot at the range session was a BUL M-5 Ultra-X and a S&W 625JM revolver… neither of those is a particularly pleasant shooter, so that may bias my perceptions. (Although, as an aside, the Ultra-X is terrifically accurate for such a little gun due to the fantastic trigger and well-constructed sights.)

To really get a feel for the gun, I need to run it in competition. This is a gun that’s good for USPSA Single-Stack, so I chose that for my experiment. I did make the modifications of blacking out the rear sight and adding large Armanov SpidErgo grips. While these do change the nature of the pistol slightly, they are also very common changes for people to make to their pistols, and thus are within the scope of the review. The SpidErgo grips add a couple ounces of weight to the gun, making it a very pleasant 35oz, and are much grippier than the factory group panels.

Unfortunately, things did not go well. It was 45f, and the gun simply would not run reliably. Lots of cycling failures that I did not experience during my indoor range testing. I assume this was due to being oversprung and having a tight rail-to-slide fit (I did lubricate before the match, incidentally) combined with a very cold day. This is not to mention that the standard-sized sticky mag release combined with the big grips did not result in very good reloads. While it is tempting to blame the shooter, magazines, or ammo, I swapped to my backup gun, and other than it shooting low (typical of Girsan 1911s), all of these problems magically disappeared using the same magazines and shooter.

After the match, I did a few (< 5) passes with a fine file to try to smooth out the magazine release cutout. I either didn’t hit the right area or there’s something else going on, because it really didn’t smooth things up much.

I called up Greg at Cosaint and let him know what I was seeing. I was really impressed at his responsiveness (try getting Ron Cohen on the phone at Sig!), and he guessed that the Cerakoting on the slide was causing the tightness I was seeing – makes sense. He told me to run 300-400 rounds through the gun to loosen it up. I suppose that’s a way to grind out some excess Cerakote, but it also seemed like a lot of money in ammunition to accomplish that (.45 Auto isn’t cheap, even reloaded). To Greg’s credit, he offered to take the gun back to the shop on his dime to resolve the fit issues. Before I agreed to send it, I did spend a little time hand-cycling the slide on the frame rails and shooting some ammo to try to smooth things out. I would say this worked somewhat, but it was still a bit on the tight side. With my experiment concluded, I sent back the gun for a touch-up at Cosaint. To sweeten the deal, Greg offered to swap out my frame for a new version that was compatible with Dawson ICE magwells. A good magwell is basically a necessity for USPSA Single Stack and IDPA CDP, so this was certainly something I wanted.

Once I got the gun back from Cosaint, it was time for some more testing. I was very pleased with what I received in the box. The slide movement was much smoother, and the magazine release had lost its stickiness (including after I replaced it with an extended Wilson mag release!). The sights were a bit off, but a bit of adjustment quickly resolved that. Actual function felt much improved; I ran a bunch of ammo with slightly high-primers through it, and it ate it all without complaint. The magazine well certainly made a substantial positive impact to my reloading, too – with a little bit of practice to get the technique down, my reloads were smoking fast (for me, anyways).

With the gun seemingly at peak function, it was time to get back to match testing. Unfortunately, the night before my chosen USPSA match, disaster struck again during dry-fire… the over-travel screw loosened and deadlined the gun! The trigger would not move at all. I was a little bit upset about this. It’s one thing for the gun to have problems during live-fire, but dying during dry-fire? That’s a real problem. The overtravel screw had essentially free movement for some reason.

I emailed Greg yet again, and he provided helpful instructions on what to do in under 12 hours. He told me the over-travel screws were staked these days, but it was not impossible that the staking job came loose. I blue-loc-tited the screw, made it flush, re-assembled the gun, and then turned the screw to the point where I no longer felt the trigger hitting the other components of the firing control group when the gun reset. Problem solved. Hopefully. I politely mentioned to him that perhaps Cosaint should go back to loc-tite.

A little more experimentation revealed that my Mec-Gar competition magazines wouldn’t lock back during live-fire. I swapped out the slide release to a Wilson GI slide release, and this problem went away.

Finally, it was time to go back to the competition test. The local IDPA club was having a low-light match, and the COS11’s accessory rail made it a perfect candidate for a spare TLR-1 HL I had lying around. With that and a PHLster Floodlight OWB holster, I was ready for some competition.

This time around, I’m happy to report it was a much better experience. The gun ran perfectly, reloads were easy with the Dawson ICE magwell, and I found the COS11 to be very accurate at practical shooting distances/targets. Ironically, the gun/ammo/me combination was so much better in terms of groups than I anticipated that I played it safe on a stage or two when I should have taken more risks! Recoil was very acceptable as well; while I think it’s hard to ever say a 45 feels like a 9mm, I found it easy enough to forget what I was shooting while distracted by executing my stage plan. Sight return was very consistent in particular. Proof is in the pudding: I took high irons at the match (albeit most of the heat was in CO), and did way better than I thought I was going to.

It took a bunch of parts replacements and a trip back to the shop, but I did get my CDP/Single-Stack competition gun in the end.

Conclusions: I very much wish I could give a full-throated recommendation of the gun given the end state and Cosaint’s outstanding support, but that just wouldn’t be reasonable given the problems described above. Unfortunately, not every review can be an unmitigated string of positives.

I think it’s clear that the out of the box experience on this example of the COS11 was not great. Every manufacturer ships a lemon or two, and I think it’s more important to see how they do with making it right than castigating them about doing it in the first place. I thought Cosaint did a fantastic job of being communicative with me and backing their own work.

Once things were sorted out (which took longer than it should have), I was impressed with how reliable it was and how well it shot, both in terms of recoil and practical accuracy. The marketing claims that this gun feels like a soft shooter are based in reality, albeit I could still tell the difference between this and a forged steel frame 1911 – no way to beat the laws of physics when it comes to sheer mass. I also liked how it didn’t give me trouble with holster compatibility, had a good fiber optic, front sight, and had an accessory rail for further customization. The shorter flush barrel was also a welcome surprise for USPSA Single-Stack usage. As a defensive gun, it probably makes the right choices for features out of the box.

That said, it’s also $1600, and with that, I have somewhat higher expectations on some of the details. The rear sight was not really optimal (albeit easily fixed with a black paint pen) – I don’t really get using a two dot sight rear with a fiber optic front even in a defensive use context. The trigger was maybe a little heavier than I wanted, albeit this wasn’t a problem for practical shooting. And, of course, there were the issues I had when I first got the gun.

The purchasing decision, I think, comes down to “what are you looking for?” In spite of the marketing, I’m not entirely sure I think a full-size single-stack gun is ideal for carry anymore, given how fantastic the Sig P365 and other micro compacts are. I do think the COS11 presents an innovative option for competition use in Single-Stack and CDP, but I would suggest you order a custom gun from Cosaint for that use case and give it a thorough workup. I will readily admit that maybe it’s not fair for me to judge a defensive pistol via competition – but I would also submit to you that performance is performance, be it at a match or in a street-level defensive use.

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