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WPB Jack: NATO-Made Poison Bullet Launcher

5.45x39mm — the famed “poison bullet” according to the Mujahadeen who first encountered the round back in the ’80s. Only a few short years ago, these rounds could be had by the case for less than $250. Thanks to the ATF and some idiot who allegedly built a pistol in the caliber, it was deemed an armor-piercing pistol round and banned from public sale.

This made the round roughly as expensive as 5.56mm for over a decade before new sanctions stemming from the war in Ukraine drove the final nails into the round’s proverbial coffin. But that’s not the end of the story for Russia’s answer to America’s favorite 5.56mm round. 

More and more ammo-makers are tooling up to churn out this round, both foreign and domestic.

So, it makes sense that new companies would start producing firearms in 5.45x39mm again. The Polish gunmakers over at WBP, in conjunction with stateside modifier Atlantic Arms Mfg., have done just that with their new 5.45 Jack carbine. 


The Jack is a very unusual gun, but at first glance, it doesn’t seem that way. The majority of 5.45-caliber AKs on the market today are based on either the AK-74M or the AK-100 series guns. The Jack is totally different; it’s an AKMN chambered in 5.45. What does this mean?

Essentially, the Jack uses a standard fixed stock, features a left-side optics rail, has a muzzle threaded to 14x1LH, and utilizes a 45-degree gas block. If most of this is meaningless to you, sit tight, we’ll explain.

AK rearsight is bone stock.

But first, let’s get into what the Jack is on a mechanical level. As an AKM, or Avtomat Kalashnikova Modernitzhy, the Jack is a semi-automatic, magazine-fed carbine that operates via a long-stroke, piston-driven action.

What does long-stroke mean? Well, in a nutshell, it means that the piston is attached to and travels the same distance as the bolt carrier group. This is unlike the majority of fourth-gen piston guns on the market today, such as the SCAR, the BRN-180, the SA-80, the PSA JAKL, or even the Bren. All of these guns are short-stroke piston guns. 

The tabbed selector and extended mag release aren’t.

With these firearms, the piston is separate from the carrier group and merely impacts or interfaces with the carrier group during the recoil cycle to drive it rearward. Most modern guns don’t use a long-stroke action because of weight and recoil.

Long-stroke guns tend to have a more violent recoil impulse because the combined mass of the carrier and piston is greater than just the carrier itself. This matters because that same weight is reciprocating back and forth during the auto-loading process of the gun. In the simplest terms, a big heavy weight slamming into the back of the receiver imparts more force and thus felt recoil on the shooter than a lighter one. 

The reason the Soviets went with this design is because it’s more reliable and tolerates more internal fouling than both direct impingement and short-stroke pistons. And if your primary theatre of operations is Russia, this is critical. And in the wise words of countless rednecks I encounter here in South Carolina, if it ain’t broke, don’t fix it, which is precisely the route WBP took. 

They simply used their experience building 7.62x39mm and 5.56mm AKs and applied it to a modified 5.45 gun. The result is a rifle that looks like the classic freedom fighter carbine and runs an incredibly light-kicking round. But before we get too far in, let’s start at the muzzle and work our way back to cover all the unique features of the gun.


Atop its 14x1LH threaded muzzle, the 5.45 Jack features a two-port brake that looks like early Norinco muzzle devices and those made in the early 2000s by Tapco. While not a “proper” AK-74 brake, it functions very well on the Jack, cutting the already negligible recoil to laughably light levels, especially when compared to 30-caliber AKs. 

The barrel itself measures 16.3 inches, made from 4150 CroMoly steel and treated to a black nitride finish for increased longevity and resistance to corrosion. This is a very welcome addition, given the mildly corrosive nature of the gold-standard 7N6 surplus ammo. It also features a Mil-spec twist rate of 1:7.87.

The 45-degree gas block might offend some purists.

Behind this, the Jack includes an AKM bayonet lug and a fully adjustable front sight tower. Further back, the handguards are made of a very handsome (yet still Mil-spec) blonde laminate wood that, in testing, did an admirable job of keeping a shooter’s hands from being burned by the barrel as it heats up. However, take care not to touch the steel pin toward the front, as it gets uncomfortably hot after about 150 rounds.

Behind the handguards, the barrel trunnion features the laser-engraved Polish Eagle coat of arms on the left side. Above the eagle, the Jack features the iconic — and optimistic — notch sights adjustable for elevation with pre-zeroed settings for distances ranging from 50 meters out to 800 meters.

The carrier is made of stainless steel, contrasting with the semi-gloss black finish of the rifle. It’d be nice if it were hard-chromed, but the stainless finish is easy enough to clean and means the gun is less expensive.

The first actual departure (other than caliber) the Jack has from your run-of-the-mill AKM is the addition of an oversized safety selector. It does a great job of striking a balance between usability and proper AK aesthetics. The same is true of the magazine release tab. It’s substantially larger than Mil-spec but makes extracting spent magazines easier.

The Jack ships with a standard AKM polymer pistol grip and a blonde laminate wooden stock that perfectly matches the handguards. And that’s the long and short of it — just a well-made AKM of a different caliber. 

However, many companies have tried to put their own spin on the AK-74 with mixed results. Some companies, like one that rhymes with “rudimentary,” used the wrong bore diameter and twist rate and saw rounds keyhole out of the barrel. Others simply installed selector plates incorrectly, leading to guns that either had dramatically increased recoil or reliability issues. So, how did WBP do? 


In testing, we fired around 800 rounds of ammo through the Jack, with the overwhelming majority being surplus 7N6 52-grain FMJ from Russia (RIP bank account). And in all this testing, there was never a single malfunction, regardless of which magazine was used. This includes the translucent polymer WBP mag that ships with the gun and Bulgarian, Russian, Romanian, and Chinese examples. Everything locked up tight and fed flawlessly.

As far as accuracy, the Jack regularly produced groups hovering around and just below two MOA. Not a precision weapon system by any stretch, but more than accurate enough. In fact, while the gun achieved very respectable groups with surplus 7N6, it shot outstandingly well with Hornady’s 5.45 SST rounds. Sadly, these are even harder to find than surplus ammo.

The worst-performing ammo of the group was Wolf 55-grain soft point ammo. Something about the consistency of the exposed lead rounds opened up groups to around 2.7 MOA. But since this ammo notoriously — and surprisingly — performs terribly in terms of terminal ballistics, there’s no love lost.


Is the new Polish WBP Jack 545 worth its $1,100 MSRP? It really depends. For shooters with a large stash of 5.45 who want a new platform to launch these rounds — yes. 

We’d also argue it’s an excellent buy for collectors and shooters who want to dip their toes in the 5.45 game but don’t want to drop over $2,000 on an Arsenal or converted Russian Saiga.

Realistically, if we wanted a low-recoil Polish AK, we’d go with the WBP Jack 556 since the ammunition is a little cheaper but vastly more available. Either way, both guns are flawlessly accurate and inarguably handsome additions to any shooter’s AK collection. 

That said, if you’ve always wanted a Mil-spec AK in 5.45, given the state of the world market at the moment, there’s no better option at this price point. 

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