Olympic Arms K23B Stubby: an obscure object of desire
Now out of production, and exported in very limited quantities outside of the United States in the past years, the Olympic Arms K23B "Stubby" is one of the shortest AR-15 variants to have ever been made available on commercial markets: let's have a look at it!
Headquartered in Olympia (WA, U.S.A.), the Olympic Arms, Inc. company was a pioneer in innovative solutions that would enhance the versatility of the AR-15 platform. Bufferless technology was their signature feature: some of the company's best known products used proprietary upper receivers that allowed to do without a recoil buffer and the relevant tube, allowing the guns to use a folding stock in lieu of the classic M4 collapsible stock – or even no stock at all.
Products such as the OA-93, OA-96 and OA-98 lines of semi-automatic rifles, short-barrel carbines and pistols were launched in the 1990s as forerunners of a tendency that seems to be living its peak in our time, as we write.
Back then, however, customization of lower receivers and recoil buffer assemblies was not à la page as it is now; thus, when Olympic Arms designed the K23B "Stubby" model at the end of the 1990s, they decided to use a standard, unmodified lower receiver as a basis. This, because while as a complete firearm it was conceived to be semi-automatic only, professional customers such as Police forces, military units or other government entities could be able to run it in full-auto by installing the upper receiver on pre-existing select-fire M16 lowers.
Given the ratio between the overall dimension and the barrel length, the designation of the Olympic Arms K23B Stubby will vary depending from local laws and regulations: in the United States it is an SBR ("Short Barrel Rifle") as per the provisions of the National Firearms Act of 1934; in other Countries, most notably some in Europe, it is considered a handgun instead – stock or not.
While it was at a certain time made available for civilian NFA sales nationally and for commercial sales abroad, the Olympic Arms K23B Stubby was conceived mainly for professional sales, more specifically as a law enforcement weapon dedicated (but not limited) to close protection details.
It was about the time when the 1997 North Hollywood shootout changed the paradigm of Police armament in the United States; all of a sudden, all cops needed a firearm that could pierce through bodyarmor – and that included motorcycle officers, who would need a firearm that would pack the punch of an AR-15 while at the same time fitting in their bikes' hard bags.
The upper receiver of the Olympic Arms K23B Stubby is an A2 model, which means that the Delta-design front sight is integral to the gas block and that the carrying hande is not removable and features an adjustable rear sight. Late production models were assembled around an A3 upper receiver, featuring a removable carrying handle attached to a Picatinny rail.
The lower receiver is a standard M4-type, with the hold-open release catch and safety switch located only on the left side, the magazine release button located on the right side, and a standard M4-style polymer collapsible stock mounted on a six-position buffer tube. The standard caliber is 5,56mm, and the K23B Stubby will reliably feed both 5.56x45mm NATO and .223 Remington commercial loads. The magazine well will accept any AR-15 type, STANAG 4179 compliant magazine.
Simply put, what we have here is a typical AR-15 shrinked down to as short as it could get: it is barely 22.5 inches long (that's about 57 centimetres), and the overall weight is set at around 2,7 kilograms, or 5.95 pounds.
The 6.5" barrel is button-rifled out of chrome-moly steel and features a free-float handguard and a four-prong flash hider; later production variants featured a machined quad-railed handguard and a variant of the birdcage flash hider dubbed the "Phantom".
Technically speaking, the Olympic Arms K23B Stubby shifts very little from a standard AR-15: the bolt carrier group is just the same, the buffer assembly is standard, same goes for the trigger.
The main difference is in the direct gas impingment system: instead of a straight gas tube, the Olympic Arms K23B Stubby features what is called a "Pigtail" gas tube – a curved tube that wraps at least twice around the barrel in its travel from the gas block to the upper receiver.
The pigtail gas tube allows the use of a full-length tube in an extremely short firearm; this reduces significatively the level of pressure exerted against the bolt carrier group. If a classic (straight) gas tube were to be used, the recoil would be extremely high and a heavier recoil buffer and buffer spring would be required to tame it.
There's no point in hiding it, not since the world's biggest experts in the AR-15 platforms have been highlighting it for years: the Olympic Arms K23B Stubby is definitely not a gun that comes without defects – and most of those defects and flaws are inherently tied to the technical solutions adopted by Olympic Arms in their quest to conceive an AR-15 subcarbine that would be just as short as it gets.
To begin with, the barrel – with its six right-handed grooves and 1:7" rifling pitch – is just too short at 6.5 inches to be a good performer with 5.56mm/.223: most experts agree that the minimum length threshold for this caliber is 11.5 inches, under which the gun can not guarantee proper ballistics.
This means that the K23B Stubby is extremely loud when fired, and produces a significative muzzle blast – as in, way too loud and way too big a muzzle blast to make the K23B Stubby viable for CQB combat indoors or in the dark.
Plus, the 6.5" barrel is just not long enough to properly stabilize the 5,56mm/.223 round, either in its commercial or military loads. All tests show that the K23B Stubby will not provide satisfactory accuracy over 50 metres; that's not much of a problem for a gun that has been conceived for VIP protection and extreme close-quarters engagements, but it's still a sign of how the design is an inherent underperformer if compared to the potential of the round.
Another drawback of the K23B Stubby is tied to the use of a "Pigtail" gas tube twisted around the barrel – a design that, indeed, has been proven to work reasonably well in taming the recoil of AR-15 based pistols and in reducing the cyclic rate of AR-15 PDWs.
But with the stress levels that are inherent to such a short barrel length, the "Pigtail" gas tube underwent too high levels of torque that would often lead it to come out either from the gas block or the upper receiver – and sometimes it even caused breakages. Either way, disassembly and gunsmithing was required to make the gun operational again.
The Olympic Arms company could have addressed the issue by implementing a different gas tube design. There are examples of gas tubes that work pretty well in ultra-compact AR-15s, such as the TwinTube designed by Tim LaFrance for his select-fire M16K.
The LaFrance TwinTube was forked and would dissipate a portion of the gases within the handguard to keep pressure levels down while at the same time remaining straight in shape to avoid excessive torque.
Of course, the K23B Stubby could also be fit with a standard, straight short gas tube purported that a heavier recoil buffer and buffer spring were used.
The Olympic Arms company probably never considered this solution because, as mentioned above, one of the requirements for the K23B Stubby was to keep the upper receiver usable with an unmodified select-fire lower. Plus – once again, as mentioned above – most of Olympic Arms' R&D aimed at doing completely without the recoil buffer and buffer tube, as the company saw it as an element that impeded the use of folding stocks and thus reduced the versatility potential of the AR-15 platform.
Under this point of view, the Olympic Arms K23B Stubby is somewhat of a lost opportunity. If some of you owns a K23B Stubby and wants to get to the roots of those inherent drawbacks, consider this as a short guide on what to do.
The Olympic Arms company ceased to exist in February 2017, after forty years of activity; the K23B Stubby had already been out of production for some time by then, but some could still be assembled on order from existing parts stocks – something that will no longer be possible now that all stocks have been liquidated.
The very few dozens of Olympic Arms K23B Stubby samples sold on the civilian markets in Europe and in the United States are thus bound to become highly sought after by collectors, with their prices bound to rise. Of course there are many similar products still being manufactured – such as the DPMS PDW, the PWS MK107 "Diablo" or the countless AR-15 based pistols and SBRs – but the K23B Stubby is what started it all.
Olympic Arms K23B Stubby - Technical specs
Semi-automatic pistol or semi-automatic carbine, depending from local regulations
5,56x45mm NATO / .223 Remington
Semi-automatic, direct gas impingment, rotating bolt
Manual safety switch located on the left side of the lower receiver
STANAG 4179 compliant AR-15 magazines of any make, material, and capacity
220 mm / 6.5"
A2 type fixed front sight, A2 type adjustable rear sight
533 mm / 20" to 571 mm / 22.5", depending from the position of the stock
2,7 kg / 5.95 lbs
Hard-anodized airspace-grade lightweight aluminum alloy upper and lower receiver; polymer (Fiberite) pistol grip and 6-positions collapsible buttstock; Chrome-Moly steel button-rifled barrel
Out of production - see your dealer for availability and pricing