Blowback action felt recoil and what it means to shooting practice Part 1
Or as Sir Isaac Newton put it in 1687,
“For every action there is an equal and opposite reaction.”
By Dennis Adler
Four ideal candidates for blowback action CO2 models with just enough felt recoil to give shooters a better sense of the gun firing in addition to slide motion. This small “kick” is less than a .22 target pistol, but enough to give some degree of feedback. Pictured are the Umarex S&W M&P40 (left and moving clockwise), the Tanfoglio Limited Custom, Umarex Beretta 92A1 and ASG CZ-75. All four have similar barrel and slide designs but only the Tanfoglio and M&P40 have barrels and slides that lock and disengage like a cartridge firing pistol.
Newton’s third law of motion is still the best explanation of recoil from a firearm, even though when he postulated his three theories of motion 330 years ago it is unlikely he was thinking about firing a handgun (unless he was familiar with Wheelock pistols), but his theory of action and equal and opposite reaction is perfectly suited to defining recoil in a handgun. Heavy recoil has never been a desirable characteristic, but it comes with the territory. This is, of course, relative to the handgun design and other mitigating circumstances, but Newton’s theory applies in proportion whenever a bullet, BB, or pellet, is fired from a handgun. What are those mitigating circumstances? With handguns it is design. The maximum example would be firing a .500 S&W magnum revolver, the most powerful production revolver in the world (sorry Harry you’ve been replaced), in which the full action of firing the revolver distributes the recoil back through the gun and into the shooter’s body. The weight of the gun itself, barrel length, as well as porting of the barrel to allow gasses to escape upward and reduce muzzle lift, and even grip design are factors to mitigating felt recoil. (Different bullet grain weights, type of gunpowder, and even bullet designs will also have a bearing on recoil). The opposite end of that extreme would be a silenced .22 caliber semi-auto which would exert almost no appreciable recoil. So why are we looking for recoil in a CO2 powered blowback action air pistol?
The example at top is a real Smith & Wesson M&P40; the other is the Umarex S&W M&P40. Both share the same short-recoil locked-breech internal design and basic operation. Both also disassemble the same.
For our purpose in Airgun Experience, recoil becomes an essential part of training with air pistols. The baseline for felt recoil in a blowback action semi-auto at best is going to be a .22 LR pistol. The examples I will be using are a target model Walther P22 with extended and weighted barrel, and a vintage Browning Medalist competition pistol. What we want to establish is minimum felt recoil and then find the blowback action CO2 pistol that most closely duplicates it. That will be the one model that earns the best rating in this exploration of blowback action semi-autos. We could cut to the chase and give the award hands down to either the Umarex Broomhandle Mauser Model 712 or Beretta Model 92A1 fired on full auto, but that is too obvious. We are going to work to find out what semi-auto, fired semi-auto has the most realistic in felt recoil. And this is a good thing for training. Learning how to work with recoil and get your handgun accurately back on target is one of the key steps in learning to shoot a pistol.
As a baseline for comparison, I will be shooting a Walther P22 target model (bottom) with extended and weighted barrel. This will produce less felt recoil than a standard P22 model and should allow CO2 models like the Umarex S&W M&P 40 (top) to feel similar, albeit much quieter.
To qualify for this evaluation the airgun must have a full length slide that locks back, an open ejection port and exposed barrel breech, and preferably a short-recoil operating design with the back of the barrel lug and slide locking together in battery and disengaging with the barrel tilting slightly downward and unlocking from the slide interface when fired. A number of CO2 blowback action models use this John M. Browning recoil-operated centerfire and rimfire pistol design, and these will have more felt recoil. The other design used in blowback action air pistols does not have tilting barrels or slides and barrels that lock and disengage as the pistol is fired.
The barrel breechblock on the airgun (left) and .40 S&W model both disengage from the slide during recoil. This is a characteristic of a short-recoil locked-breech design.
These will usually have much shorter and lighter recoil since the slide travels only enough to re-cock the hammer or internal action. This is exemplified by pistols like the Umarex Colt M45 CQBP, ASG Bersa BP9CC, and Sig Sauer Spartan, which have the barrel butted to the CO2 system (they also generally have higher velocities). When the slide moves back (or you manually push it back) there is no exposed barrel breech and you cannot see into the gun. And they all use stick magazines. For the purposes of this test, those guns and CO2 models using similar systems are disqualified (though some do produce a fair amount of felt recoil like the Sig).
Here the .40 S&W model’s barrel breechblock tilts down as the slide moves back…
…the Umarex M&P40 operates the same with the barrel breechblock tilting down as the slide retracts. The Tanfoglio works identically. The Beretta and CZ-75 do not have tilting barrels, but otherwise use a blowback action version of the short-recoil locked breech design with a guide rod surrounded by a recoil spring coupled to the barrel lug.
With simpler (less expensive) blowback action CO2 models like the Umarex Colt M45 CQBP (which does have working ambidextrous safeties) the barrel is butted to the CO2 system, and thus you cannot see inside the pistol, the magazine or BB to be fired. These pistols generally all use stick magazines and not self contained drop free CO2 BB magazines.
In this series of articles we are not looking to control recoil, but rather see it, so all of the tests with the .22 LR pistols and with CO2 models will be done using a classic one-handed target shooting stance. Since I am the test subject, the recoil measurement will be very subjective, i.e. how the gun feels in my hand and how much perceived recoil is felt. Obviously, every individual is going to handle recoil differently. I have watched Rob Latham (captain of the Springfield Armory team) shoot and he has arms like an athlete, so his perception of felt recoil is going to be different from mine. I manage recoil pretty well (but I have been shooting handguns for over 40 years) so what I feel in firing these two .22 caliber pistols and a series of blowback action CO2 models is going to be pretty accurate for an “average” person. The airgun that wins in this competition will be the one that I feel comes closest to a .22 LR target pistol. That is the most you can expect from a 12 gr. CO2-powered blowback action semi-auto that has to use a compressed air charge to simultaneously send a .177 caliber projectile downrange and drive the slide back to re-cock the action. But remember, that is exactly what the gasses created by firing a .22 LR cartridge have to do in a blowback action semi-auto! Action, reaction; Newton’s law applies equally to air pistols.
This overhead view clearly shows the difference in blowback action designs with the Umarex M&P40 compared to the Umarex Colt M45 CQBP. Both have the slides locked back and magazines removed. You can see straight down through the M&P40 because the barrel is completely disengaged from the slide (like a cartridge-firing model), while the CQBP remains with the barrel in place. You can also note that even though the Colt M45 airgun has a longer barrel and slide than the M&P40, the slide on the S&W airgun retracts all the way back like the .40S&W and 9mm models. The slide on the Colt only retracts far enough to re-cock the hammer and actually comes up even to the back of the beavertail grip safety rather than going beyond it like an actual 1911 slide.
In Part 2 the shooting comparisons begin.
In centerfire handguns the emphasis is decreasing recoil . For airguns it is increasing recoil and being able to create more realistic blowback . It may be worth looking at probably the first handgun to attempt this, the Colt 22Ace . At first a steel slide was used , but the 22 could not reliably cycle the heavy slide . Two things were done . A lighter weight slide and the innovative floating chamber . It would be interesting to see if a similar approach could be used in blowback air pistols to create more felt recoil , and not sacrifice velocity or reliability.
Has anyone designed and manufactured any kind of pistol mount with a spring gauge that can measure recoil in a fashion similar to measuring trigger pull weight with a trigger gauge? This felt recoil evaluation would be better if the amount of recoil could be measured and quantified.
Yes and we will be discussing that in Part 2, but it isn’t exactly what you are thinking about. I’m not sure how your suggestion would work, but I like the concept.