SIG MCX Gen 2 Pellet Rifle Review, .177 Caliber


Testers: Doug Wall, Stephen Archer

Caliber: 0.177 cal.

Model Number: AIR-MCX-177-G2-BLK

Test Date: Sept 9, 2022

Serial Numbers: 22E 0769-0

Source of Supply: Supplied by SIG-SAUER

Condition: New.

We Like


Build Quality

Shot Count

We Don't Like

Slow Loading

No Full Auto

Really A DA Revolver Action


  • Value for Money
  • Comparison to Makers Claims:
  • Consistency
  • Appearance and Finish
  • Buying and Owning
  • Realism, Look & Feel
  • Realism, Trigger Action
  • Accuracy & Point of Aim
  • Shot Count
  • Muzzle Velocity



The SIG MCX Gen 2 pellet rifle is a huge improvement on the “Gen 1” version tested by HAM way back in 2016.

SIG has been quietly working-away improving the performance of their CO2-powered long guns and it shows, particularly in the much-improved accuracy! Overall, this Gen 2 model is a formidable competitor in the current “firearms replica/plinker” market.

Of course, this is not a SIG replica, it IS a SIG. That means a lot to many people and they will certainly be pleased by this new model.

Overall, this MCX Gen 2 is a very strong HAM Silver Award performer. Recommended!


Selling for a Street Price of $199.99, the CO2-powered SIG MCX Gen 2 pellet rifle is $20.00 more than the previous version. It’s also $40.00 less than the similar-looking Rattler Canebrake that earned a HAM Gold Award on test in 2021.

So how does the SIG MCX Gen 2 pellet rifle perform? The answer is very well. As you’ll read below, HAM testing found it to be slightly more accurate than the Canebrake at 10 Yards, although rather slower.

Canebreak specs call for a maximum Muzzle Velocity of 600 FPS, compared to 545 FPS for the MCX Gen 2. In both cases, HAM testing found these specs were handily exceeded.

The MCX Gen 2 pellet rifle incorporates a new “flat” trigger blade. There’s also a revised pistol grip and buttstock. Compared to the “Gen 1” MCX, the KeyMod accessory slots in the fore end are replaced by more modern MLOK slots, too.

Overall, the MCX Gen 2 pellet rifle starring in this test offers more power and significantly better accuracy than the original MCX tested by HAM back in 2016. It’s also selling for $70.00 less than the price six years ago.

All these are good things and enable the new Gen 2 MCX to easily justify a prestigeous HAM Silver Award for its performance, quality and value!

SIG Sauer MCX Pellet Rifle Gen 2, Black 0.177



The SIG MCX Gen 2 pellet rifle rifle is a close representation of the centerfire model in most respects. All – that is – except for the buttstock. Instead of the firearm’s side-folding stock, there’s the fixed tubular stock containing the 88/90 Grain CO2 cartridge.

There’s no way out of this situation: it’s just how the airgun platform is designed.

Moving on from the stock, the MCX has representations of all the major features and controls of the centerfire model. The ambidextrous safety, magazine release and charging handle are all functional. However, the bolt catch and left side mag release are not, nor is the ejection port cover.

The “silencer” is also non-functional, although it’s not really needed by the power output of this gun.

Like the firearm, the MCX Gen 2 pellet rifle has a plethora of Picatinny, M-Lok and QD sling mounting points. So there’s a huge range of possibilities for accessorizing your air rifle.

For example, we added UTG Recon Flex M-Lok bipod legs from Leapers, as you can see from the photographs. These provided a solid, firm mounting for shooting the MCX from a fixed position.

There’s also a new pistol grip. It’s comfortable to hold but has a curiously-unfinished appearance due to the lack of a external trap door or cover.



The SIG MCX Gen 2 pellet rifle is supplied with SIG Air’s standard fold down (BUIS) iron sights. These are adjustable for elevation and windage in the standard manner of “M16” sights. The front sight is elevation-adjustable (using the supplied tool).

The rear sight has windage adjustability, also using the same tool. It also includes small and large rear apertures, just like those of the centerfire models.

However, the MCX also includes a long and very solid top Picatinny rail. We mounted a Leapers UTG Bugbuster 3-9 x 32AO scope there, together with a UTG riser to achieve a more comfortable eyeline when testing the gun.

The UTG Bugbuster matched well with the MCX for size and looks. It also is suitably compact and – with its close-focusing capabilities – ideal for the typical types of shooting that a MCX owner would undertake.

At 10 Yards range, every shot fired in this HAM test review hit easily inside the “bull” on our soda can target at 10 Yards, as you can see from the targets at the foot of this review. This was superior accuracy to the Canebrake tested last year.

At 25 Yards, 9 out of 10 shots hit within the soda can. While not quite as good as the Canebrake, it shows that the SIG MCX Gen 2 pellet rifle can be a capable plinker or firearms trainer.



SIG claims that the MCX Gen 2 offers “authentic weight, balance and handling”. As the HAM Testers have not handled the firearm version of the MCX, we believe this to be true based on Internet searching.

Of course, the next main claim for this new MCX is Muzzle Velocity. The maximum is listed as “up to 545 FPS” right on the box.

This we can test! The gun tested by HAM developed a maximum of 608 FPS at 69 degrees F.

Based on testing with other CO2-powered air rifles, we would expect the muzzle velocity of the MCX to increase by about 2 FPS per degree Farenheit and to peak at a temperature approaching 95 degrees.

This represents no less than 650 FPS at 90 degrees F with the lightest alloy pellets. So the MCX Gen 2 has the potential to exceed SIG’s claim by no less than 105 FPS. And all you need to do to benefit from this velocity increase is to shoot the gun on a hot day!

SIG claims that the SIG MCX Gen 2 pellet rifle has an improved trigger. Judging from HAM testing, there’s certainly a difference – and a good one at that.

The “Gen 1” MCX tested by HAM gave an average trigger pull weight of 8 Lbs 11 Oz.  The Canebrake tested at an average of 8 Lbs 8 Oz. Now the SIG MCX Gen 2 pellet rifle gave us an average pull weight of 6 Lbs 13 Oz.

That’s a big difference and it makes the Gen 2 model much easier to fire for extended periods of shooting.

But HAM does disagree with SIG’s claim that the MCX has a semi-auto action.  This claim is made primarily on the back of the retail box where – possibly – it might impress purchasers in “big box” retail stores.

However, it’s not correct. At least in the normally-accepted meaning whereby the firing of a shot automatically chambers the next round, that is.

The MCX Gen 2 air rifle may FEEL like a semi-auto, but it actually uses a double-action revolver mechanism to advance the next pellet. That’s one reason why the trigger pull weight is relatively heavy!

If you look up inside the open magazine well, it’s easy to see that pulling the MCX’s trigger operates a lever that engages the toothed magazine belt and rotates it by one chamber. That’s DA revolver operation and it’s the same as is used in all SIG’s pellet guns.

Of course, many owners will not care about this. There’s no doubt that the SIG MCX Gen 2 pellet rifle goes bang each time the trigger is pulled. It feels like a semi-auto and that’s probably good enough for many. Knowledgeable owners will understand and accept the action for what it is…



At an average of 15.9 FPS Standard Deviation, the measure of FPS variability within a shot string, was acceptable for a CO2-powered airgun with the range of standard HAM test pellets.

Trigger pull weight of the averaged 6 Lbs 13 Oz. Six out of the seven measurements were between 6 Lbs 9 Oz and 6 Lb 13 Oz – which was extremely good. However, then we measured the final one at 7 Lb 8 Oz.  Aw shucks…



We’ve already reviewed the action in the “Comparisons” section of this review above. So there’s no need to cover it further here except to mention that  – as with all SIG CO2-powered long guns – there’s no blowback effect in the Gen 2 MCX.

The metal trigger blade pulls back through a long “first stage” until a significant, but predictable, resistance is felt. Pull back hard and the gun fires after a short further travel.

HAM tester Stephen Archer considered the trigger pull felt best if it was pulled back fast and hard – as would be done in the heat of battle with the MCX firearm. That gives shooting high on the fun factor but is not best if the aim is pinpoint accuracy.

Although that – close to 7 Lb – trigger pull weight sounds heavy, it actually didn’t feel too bad at all. Probably this is because of the comfortable hand position provided by the pistol grip and the substantial overall weight of the MCX. The gun weighed-in at 9 Lbs 3 Oz with scope installed.

There’s a very effective, ambidextrous manual safety. Located just above and to the rear of the trigger, it’s ideally placed to be operated by the thumb of the trigger hand. Push down to fire, up for safe. Unfortunately, there’s no full auto, “fun setting” as is found on many BB-firing CO2-powered long guns…

The ambidextrous cocking handle (equivalent of charging handle on the firearm) is very light and easy to use. As you’d expect, it’s only operated once on inserting a new magazine and so the cocking effort for the MCX Gen 2 pellet rifle is close to zero.



The large 88/90 Gram CO2 cartridge, combined with the lack of energy-absorbing blowback action, means that the MCX Gen 2 gives a good number of shots before re-filling.

In HAM structured testing, we fired over 200 shots on the same, original CO2 cartridge.

Your mileage may vary depending on your shooting conditions, but it should be in the 250 – 300 shots range.



The SIG MCX Gen 2 pellet rifle tested by HAM gave respectable performance for a CO2-powered replica airgun. Muzzle Energy peaked at 4.5 Ft/Lbs with light alloy pellets, while the maximum velocity was 608 FPS, achieved with the light Predator GTO alloy pellets.

PelletAverage Muzzle VelocityAverage Muzzle EnergyAccuracy
Predator GTO 5.0 Grain608 FPS4.52 Ft/LbsVery good.
H&N Field Target Trophy Green 5.56 Grain604 FPS4.51 Ft/LbsExcellent.
RWS Hobby 7.0 Grain542 FPS4.57 Ft/LbsExcellent.
Crosman Premier HP 7.9 Grain489 FPS4.19 Ft/LbsVery good.
JSB Exact Diabalo 8.44 Grain467 FPS4.09 Ft/LbsVery Good.
H&N Field Target Trophy 8.64 Grain463 FPS4.11 Ft/LbsExcellent. Best Tested.
H&N Baracuda Match 10.65 Grain417 FPS4.1 Ft/LbsVery Good.

HAM agrees with the manufacturer’s suggested use for the MCX: plinking and firearms training. It does not have sufficient power for any type of hunting – even for small critters at close range – if the desired result is a humane, one-shot kill.



As with all SIG Air products, the appearance and finish of the MCX Gen 2 is outstanding!

The quality of the cast and molded parts that comprise the majority of the external surfaces is very high, as you can see from the photographs throughout this review.

All external parts are beautifully finished and assembly was obviously fastidious.

Yes, this is yet another “black rifle”, but close examination reveals precision molding of the synthetic parts, high quality metal castings and a range of high quality surface finishes.



The MCX Gen 2 pellet rifle uses the now-familiar SIG 30-round magazine.

Loading is quite easy. Drop the magazine, open the sideplate and pull out the empty 30-round belt. Seat pellets in place using the loading/sight adjustment tool that’s bundled with the gun.

However you do have to treat the loading process with some respect and have a solid table top (or similar) to do it on. This is not a process you want to undertake in the field.

As you’re going to be doing lots of shooting with the MCX Gen 2, it makes sense to buy at least one additional magazine. Each spare SIG magazine is supplied with a total of three belts. So, with a spare magazine, you have a total of four belts for your gun. That gives a total of 120 pellets that can be loaded before you start pulling the trigger. That’s the way to do it!!!

Sliding loaded belts into an open magazine is quick and easy. This can be done without the support of a table. Once the pellets are loaded into belts, the re-loading speed is likely quicker than that of re-loading a BB-shooting gun.

In addition, the SIG’s large – 88 or 90 Gram – CO2 supply means that stops to reload CO2 cartridges are happily infrequent compared to other fast-firing CO2-powered firearms replicas using 12 Gram cartridges.

Note that the magazine does not drop free, however. Two hands are required for removal. This is not an issue for plinkers. However it’s a disadvantage where the CO2-powered MCX is used as a training tool for firearm users.

In a sign of the times, no hard copy owner’s manual is supplied with the MCX Gen 2 pellet rifle. Instead there’s a simple, one-page “Quick Start Guide” in English only that’s basically a list of warnings. This incorporates a QR code that directs the owner to a full manual on the SIG web site.

Manufacturer’s warranty is 180 days from the date of purchase. Is this good? Well, many CO2-powered airguns have just 90 days manufacturer’s coverage, while others go to 12 months. So, statistically, we’ll have to say that it’s average.

SAFETY FIRST. Due to the realistic appearance of this product, handle it as you would a firearm. Do not display it in public or in any place where it could be mistaken for a cartridge firearm.



MCX Gen 2 Pellet Rifle Review

MCX Gen 2 Pellet Rifle Review

MCX Gen 2 Pellet Rifle Review

SIG MCX Gen 2 Pellet Rifle Review

SIG MCX Gen 2 Pellet Rifle Review

SIG MCX Gen 2 Pellet Rifle Review

SIG MCX Gen 2 Pellet Rifle Review

SIG Sauer MCX Pellet Rifle Gen 2, Black 0.177

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