Kahr Mk40 Micro

Guns Magazine, April, 2000 by Massad Ayoob

The world's smallest .40 S&W self-defense pistol offers the power and accuracy you'd expect in a full-size handgun.

Kahr Arms has made quite a reputation for itself in the few years it has been producing its innovative little concealed carry pistols. They are remarkably accurate and reliable with factory ammo, though occasionally they'll throw their first hand-chambered shot to a slightly different point-of-aim than the mechanically cycled follow-up shots. Seasoned shooters trying them for the first time invariably remark on the smoothness of the Kahr's DAO trigger stroke.

Now Kahr has introduced its smallest gun yet, the Micro Kahr. It holds five .40 S&W rounds in its magazine and a sixth, safely, in its firing chamber. Yet the Micro Kahr MK4O is only 5.35" long with its 3.09" barrel, 4.55" high from butt to top of holstered gun, and measures only 0.94" wide. It weighs 23.1 ozs. unloaded, which is only .1 oz. more than the pistol that has been the definitive .380 pocket automatic since the 1930s, the Walther PPK.

Smallest Of The Small

These Kahr MK40 pistols are small and slim. The first Kahr was the K9, a compact pistol that held 7 1 rounds of 9mm. It was followed by its near twin, the K40, which held 6 1 rounds of .40 S&W Next came their first "Micro" Kahr, the MK9, a tiny 9mm that held seven rounds total, shortened at both butt and muzzle.

Attempts to make a similar size reduction on the .40 proved frustrating. The slide velocity of the much more powerful .40 S&W cartridge was difficult to stabilize on anything smaller than the already compact K40 slide.

Kahr chose a compromise route, the K40 Covert, which mated a regular (compact) K40 barrel slide assembly with the short (subcompact) grip frame of the MK9. It proved to be a nice little gun. Still, the market clamored for a .40 as small overall as Kahr's Micro 9mm.

Research continued, and the MK40 Micro was at last ready for shipment by summer of 1999. What got them over the hump was a couple of engineering tweaks: increasing the mass of the slide, and installing the captive double-spring recoil spring design pioneered by Seecamp. Kahr Arms negotiated with Seecamp and paid for the right to use the patented recoil spring system in their guns.

You'll find that about 1 oz. has been added to the slide of the MK40, and that it's a whisker higher at the rear, with more mass at the area at the back of the slide of this striker-fired pistol. This part of such a gun is commonly called the "slide cover." It doesn't change the dimensions enough to interfere with holstering.

I found this pistol would adapt nicely to other Kahr holsters from Alessi, DeSantis and Mitch Rosen. Because of its rounded edges at front and back, it also fits very nicely in elastic bellybands, a natural home for self-defense pistols of this size and shape.

The engineering tweaks were done by Justin Moon, the prime mover at Kahr Arms who came up with the basic pistol design. Would they make a gun this small work with powerful .40 S&W ammo? I took it to the range to find out.

A Popular Pistol

Everybody on the range wanted to shoot this little gun. Some brought their own ammo. I lost count of how many times the MK40 was discharged, and can only guess it to be somewhere short of 1,000 rounds. I did, however, keep count of malfunctions.

There were only four, none of which I can really blame on the pistol, at least not entirely. Two occurred during accuracy testing. The last spent casing from a string of five was jammed in the ejection port while testing the Cor-Bon 165 gr. hollowpoint.

As it says on the T-shirt the ammo manufacturer offers, "Cor-Bon Is Hot Stuff!" The 165 gr. JHP has a nominal velocity of 1,125 fps. Cor-Bon advertises it as " P ammo. Now, SAAMI has set no industry specifications for a " P" power level in .40 S&W, but if they do, Cor-Bon will define what it is.

Remember, the .40 S&W cartridge is a bigbore round designed to work in the envelope of a pistol designed for the generally less powerful 9mm. Firing .40 S&W causes slides to run faster than 9mm. Get into P .40, and the slides run faster yet.

This is no problem in a big service pistol. One year, Taurus provided .40 caliber pistols and Cor-Bon provided the ammo for a side match at Second Chance. The Taurus guns worked like champs; the Cor-Bon .40 ammo blew the heavy bowling pins off the tables as if they'd been smacked with .45 slugs and all was well with the universe.

But the Taurus .40 is a big pistol, bigger than many .45s. The Kahr. MK40 is smaller than some .380s. I think the hot load was just running the slide too fast for the cyclic rate too keep up.

Aggressive Testing

The second malfunction also occurred in the accuracy testing stage, a feedway stoppage with a CCI Blazer 180 gr. plated hollowpoint. In a tradition begun long ago with their "flying ashtray" .45 bullets, CCI produces a very "aggressive" hollowpoint projectile with a very wide mouth. Unless you have straight-line feed or a gun especially designed for such a bullet, it can hang up on the way in. We only had one such malfunction with the Kahr, however.