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Are blowback CO2 airguns worth it?

Are blowback CO2 airguns a waste of gas or just darned good fun? Jonathan Young sets out the case for CO2 guns that come with a blowback action

This is the Umarex Walther PPK/s – it may be a tiny pistol, but it still has a blowback action and James Bond would approve

Blowback CO2 airguns are all the rage, but it wasn’t all that long ago that airguns like these didn’t even exist. Traditional CO2 pellet pistols performed superbly without blowback, and the only items to have this were low-power butane or green gas replicas that were designed with blowback for more authenticity. Made in the Far East, these airsoft replicas were intended for wargames skirmishing, re-enactment and also as just very cool collector pieces.

More effective and powerful CO2 gas has been around for a very long time. Even before the last war it had been used for bulk-filling airguns with internal reservoirs. 

The late 1940s saw the first air pistol to use disposable CO2 soda siphon bulbs, the Schimel Gas Pistol. Since then, CO2 air pistols were developed by manufacturers like Crosman and Daisy ad infinitum. Blowback CO2 guns, however, never really featured, with only a few designs being given some form of cycling action.

Things changed in the 1990s, however, when Daisy released the nearest thing to what we know today as a blowback air pistol – the 2003 Multi Shot Repeater. This big lump chucked 35 pellets, not BBs, out of a removable cylindrical magazine with blowback added for free. What an airgun it was! If you could only get past how it looked. 

Joking aside, this is one of the very few inventive airgun designs that combined CO2 and blowback. The Model 454 was its BB version, and just as ugly. A third release was the Model 400, another BB-firer, but being based on the Israeli Military Industries Desert Eagle was thankfully much easier on the eye. Some years later, and dropping out of nowhere it seemed, Umarex released their blowback Walther PPK/s. Then nothing more for years.

Something was happening, but elsewhere. CO2 as a power source had not been adopted into the replica toy gun phenomena. Despite competition from green gas and electric motors with big battery packs, it was inevitable there would eventually be a crossover. Disposable CO2 bulbs quickly became a popular alternative power source. 

This resulted in many new releases with even more authentic blowback. Eventually the Asian market geared up, and today most of these 6mm releases are parallel produced with 4.5mm BB versions. Both can be identical, save for the few parts that accommodate the difference in calibre.


Blowback CO2 airguns – a familiar style

Look inside many and the airsoft layout is instantly recognisable. The drop-free magazine almost always vents CO2 upwards, which when installed in the frame passes the gas into a hollow housing. This leads forward to the barrel, and more importantly rearward to a piston housing in a small tube. Note the use of the word importantly here for later dissection, as what else is more important in airgun terms than getting the power to where it is needed most – behind the projectile?

Buyers expect to see full recoil with a semi-auto replica. The top slide or some major part of the gun will react, causing a physical interaction between the moving parts. Any Colt 1911 replica pistol will slam that top slide all the way back, while a P08 will eject that Luger toggle straight up, and any Mauser Broomhandle clone will eject the fake bolt breechblock rearward with each shot. That this has little to do with real airgunning and more to do with authentic simulation seems immaterial.

Blowback CO2 airguns

This is Umarex’s original non-blowback P08 Luger, which arguably makes it a better pistol, but does that make it more fun?


Blowback CO2 airguns – assessing the accuracy

Sealing, essential to CO2 airguns, is minimal. It must be said however that it is astonishing just how well many blowback CO2 airguns perform given these variables. The only downside is that most are fairly low in power as a direct result of all this gassing about. In reality, true airgun performance is hampered by blowback, but we don’t dare complain. 

To guarantee easy loading, each shot must rely on blowing or knocking a BB off a magazine stack, not by an accurate loading procedure as with single-shot designs. Some rely on oversized barrels to prevent BBs from jamming during the physical commotion of blowback, which means some aftermarket accurising is advisable.

Although loved for its uniqueness long before other blowbacks flooded the market, many accepted the relatively poor performance of the Umarex Walther PPK/s – before a tune that is. After some attention, a totally different story emerged. Some of the best-performing replica air pistols have been, unsurprisingly, non-blowback designs. The initial Luger or P08 replica air pistol, the Umarex Legends P08, lacks blowback, but as a direct result enjoys considerably higher muzzle velocity. Upon the arrival of the KWC P08 with its dramatic blowback, this previous Umarex design was deemed less desirable despite it having a more inventive mechanism and performance. 

However, the push for blowback has thrown up some curiosities that allow the best of both worlds, especially in designs that prioritise the transport of BBs, which makes for a better airgun.

One such is the first Gletcher P08. This pistol has blowback, but also allows the BB to be seated into the barrel first. The leading BB is transferred by a trigger-actuated push rod into the bore, whilst on firing enough CO2 is siphoned rearwards to create a cycling effect to re-cock the hammer. 

Blowback CO2 airguns

The Gletcher P08 is a bit of a hybrid, as it seats the pellet before the blowback action really comes into play

To some, the blowback action appeared to be less dramatic, with the toggle not dancing as high. This is not an accurate assessment if the gun is being shot for performance, however, especially as the inner barrel on this unique design is also held rigid for accuracy, unlike those seen on many other blowbacks. There are many other designs too that copy or adapt these ideas for a better performance.

Examining a single-shot clunky Crosman 2240 pistol in .22 calibre or any of the .177 Umarex pellet repeaters, no BB blowback pistol can come close in terms of performance and accuracy, but that said life would be rather dull without a blowback Broomhandle or Luger to play with. 

We now have pellet revolvers that can fill that obsessive niche for target gun accuracy, especially as many are now being released in pellet-firing mode. Love it or loathe it, blowback has expanded the air pistol market and we are all quite happy to continue shooting our BB blowback repeaters. 

Blowback CO2 airguns

Blowback transfers well between a 6mm airsoft and a 4.5mm airgun, with a reduction in the size of the ball ammo almost all that’s needed