When I was working through the best .45 pistols for concealed carry, I hadn’t yet had enough time to test Cosaint Arm’s new COS21 Compact Double-Stack 1911 .45 ACP. However, I included a mention of the gun because I could tell the COS21 would be a high-quality custom compact concealed carry .45. A live-fire evaluation proved my prediction correct.

Cosaint Arms

Cosaint Arms says on its website that Cosaint is a Gaelic word meaning protect or defend, which is an excellent way to describe a compact, big bore pistol like the COS21 in .45 ACP. Located in Flat Rock, North Carolina, Cosaint Arms was founded by Greg Mooney, who spent 30 years in the shooting sports industry. Having spent several years at STI International, manufacturer of the Staccato modular 1911, Mooney’s Cosaint pistols bear a remarkable resemblance to Staccato pistols. The Cosaint Arms’ mission is to bring the shooting public hand-fit, customizable guns, meeting customers’ needs and priorities.

About the COS21 .45 1911

The COS21is a modular-framed, double-stack compact .45. Its modular frame makes it easier to carry than earlier double-stack .45s that felt ungainly in-hand. The lower receiver, from Picatinny rail back to the grip and thumb safeties, is all steel. The front of the lower receiver, which extends down to the grip screws — one per side — as well as the front of the slide are flat, giving it a monolithic 21st-century appearance.

The remainder of the grip frame is made of a polymer known as PA-12, which is chemical- and shock-resistant. This polymer narrows the diameter of the grip compared to older double-stack .45s like the Para-Ordnance 14. A variety of grip colors are available with a molded in Cosaint Arms emblem. With specialized stippling, the grip frame is very comfortable and should provide a great gripping surface that won’t snag or catch on clothing.

Cosaint Arms sends two flush-fitting stainless-steel MBX 12-round magazines for the 12+1 capacity gun. These fit very close to flush with the grip frame. The COS21 is equipped with a beavertail memory bump grip safety and ambidextrous extended thumb safeties. Unfortunately, the slide lock/release lever is a standard type. With the slightly wider grip frame, I can’t reach the release lever without rotating my hand, slowing reloads. I’d prefer to see an extended slide release.

COS21 .45 ACP 1911 Specs

Barrel length: 3.5 inches
Overall length: 7.5 inches
Width: 1.375 inches
Height: 5.5 inches
Weight: 26 ounces (unloaded)

The aluminum, anodized blue trigger on my sample is flat faced yet comfortable, and the pull weight is spec’d at 3.5 pounds. The trigger is very crisp, and my shooting partner rated it better than the trigger of his compact 9mm Staccato. The trigger guard is flat faced and similarly stippled, following 21st-century styling cues. Both front and rear grasping grooves are the modern, wide style.

The 3.5-inch bull barrel is subtly V-ported, with three vent holes on each side. Though fashionable these days, there are, thankfully, no other cuts found in the slide to distract from the COS21’s looks or function.

While my COS21 came with a Trijicon RMR Type 2 RM09 red-dot pistol sight mounted on the optics-ready slide, you can order you COS21 with the basic sights of tall irons: a green-light-gathering pipe for the front sight and a plain black U-notch rear sight. The tall-mounted iron sights co-witness through a red dot sight better than any I’ve seen. The Cosaint sights are prominent enough that the rear sight can quickly lead your eye to alignment with the red-dot under most conditions. While the plain black sights won’t help you align your eye with the Trijicon glowing red dot in total darkness, it does so under reasonable lighting conditions.

Shooting the COS21 1911

I tested the COS21 with two loads: SIG Sauer 230 FMJ Elite Ball, loaded to 830 feet per second and delivering 352 foot-pounds of energy at the muzzle; and SIG Sauer Elite V-Crown JHP self-defense, loaded to the same velocity and muzzle energy. Testing inside my friend’s indoor barn range, we fired at a B27 PROS Silhouette target from 25 feet. With a two-handed grip, I shot the Elite Ball ammo first, resulting in of the best groups I’ve had with a .45 Automatic. All 11 rounds (the magazine wasn’t yet broken in enough to load 12) were in a single hole at the bottom of the orange X-ring. The sights aligned nicely with the Trijicon red dot right on top of the front sight post as round after round struck home.

I credit the high quality of both SIG Sauer loads, the Trijicon RMR sight plus the iron sight setup, and Cosaint’s COS21 pistol for this remarkably precise shooting. This is a fighting pistol set up with practical match features, including an especially fine trigger. The ported muzzle also likely helped keep the sight dot locked on target. My shooting partner agreed, saying “This is the best .45 I have ever shot. If I was interested in buying a .45, the COS21 would be the one I would purchase.”

There were no failures to feed or eject, as one should expect from a pistol in this price range. Accuracy was phenomenal, and it was also easy to control during rapid firing. The COS21 is simply a great pistol.

Should You Own a Cosaint Arms COS21?

The Cosaint COS21 is a smooth shooting firearm. AT 26 ounces unloaded, it’s easy to carry all day without undue discomfort. Its high-capacity magazine and extreme accuracy potential make it a great pistol to have in any self-defense encounter. Its trigger is far superior to that found on any of the striker-fired polymer framed guns on the market. Cosaint has a wide variety of multi-use 1911 pistol models available for order and custom build. Available caliber options include 9mm, 10mm and .45 ACP.

Sources

Cosaint Arms: CosaintArms.com
SIG Sauer: SIGSauer.com
MBX Extreme: MBXExtreme.com