You may have heard of Nuprol before, but most likely in the context of green gas or accessories. Now, however, they’re breaking into the AEG market with a collection of AR variants.
We’re taking a look at the externally most interesting and unique variant, the Delta AK-21, which replicates the real world Faxon Firearms’ ARAK-21 modular rifle. The ARAK’s main feature is quick adaptability to different ammunition loads by utilizing an adjustable gas system as well as the ability to move from one caliber to another via a quick barrel change system. To date no other airsoft version of this particular rifle exists, so if you’d like to get your hands on one, this is your chance. This item was generously provided for review by Gunfire. At the time of writing the gun retails for 362.41€.
First impressions
Contents of the package sit snugly inside form fitted foam, and include the rifle itself as well as a metal hicap magazine, front grip, user guide, extra body pins and, curiously, rail mounted offset iron sights.
The rifle itself looks good and the upper receiver matches its real world counterpart quite faithfully. Not so on the lower, however, which replicates the look of a standard, forged AR lower. Faxon offer the complete rifle with a specific, billet type lower with a rounded trigger guard. The real world gun also comes with an ergonomic pistol grip instead of the standard A2 style seen here. It’s unfortunate that Nuprol have chosen to not follow through to the end and deliver the complete, unique package.
On the outside, the gun is literally plastered with different warning labels, which rather detract from the overall aesthetic, but at least they are easily removable.
One warning label states the gun will shoot under 1.2 J. A quick run through the chroho with zero hop up gives out readings of 1.0 Joules. Considering the fact we’re looking at a full length rifle, this seems rather low. Typically guns in this category chrono around the 1.6 J mark. While power isn’t the be all end all, you may find yourself outmatched at longer ranges in field conditions.
Wiring is done to the rear using mini Tamiya connectors, with the SOPMOD style stock able to store a nunchuck type battery.
The most remarkable feature immediately noticeable when working the gun for the first time is the trigger. The feel is really crisp and unlike most AEGs. There’s a definite similarity to a real firearm, with a short soft pull followed by a noticeable step, after which the gun fires. This is due to the trigger controlling a micro switch instead of the more typical copper contact connector, resulting in the different feeling. The motor response is also very nice and snappy.
Externals
As mentioned above, the externals are quite well made, although there is sadly some minor wobble between the upper and the lower. Small details like the gas port adjustment knob and charging handle have been modelled faithfully.
The rear sling plate is steel for added durability. Magazine release button and parts are typical screw fastened bits, none of which are steel. The gun has a bolt hold open analogy, which allows for hop-up adjustment after pulling back the charging handle. 
The lower receiver is your standard AR fare with no discerning features, apart from the fact that the magazine well measurements do not seem to correlate to a lot of other manufacturers. This is evident from the fact that the Nuprol high capacity magazine accompanying the gun does not fit at all into, for example, a Specna Arms or ACM lower. Conversely, PMAGs and Dboys metal STANAGs have trouble staying put in the Nuprol mag well. A bit of wiggling and you can pull the magazine out without touching the release. While this is easily fixable with a bit of padding on the inside of the mag well opposite the catch, it’s not something you’d expect to be doing to a gun in this price range.
Internals
Moving on to the inside, the first thing you’ll notice is that the front pin is seriously tight. This is mainly due to a rather hefty spring pushing the hop up against the gearbox. Most springs like this are usually quite lackluster, so it’s good to see a proper stiff spring doing what it’s meant to.
The inner barrel is made of steel. The hop-up unit is a typical plastic AR one with a rotary wheel on the side. On my review sample, the barrel was not aligned properly in the HU unit, resulting in the bucking protruding more on one side. The bucking surface also seems not to be smooth. More things you’d expect to not face in a gun with this kind of pricing.
Looking into the hop-up unit from the rear
The poor QC shows also in the insides of the upper, where there are some metal shavings present, as well as a small bit of rust on one screw head.
The motor is a nondescript, unmarked, ferrite magnet one. The pinion is D shaped, and the gear is secured with an allen screw. Wiring inside the grip is done with both wires running from behind the motor.
Moving on to the fairly standard V2 gearbox, the most noticeable feature is the quick spring change. The end of the spring guide takes a 6mm allen key, and with a push and a quarter twist, the spring comes loose. The gearbox needs to be loose from the gun for the spring guide to be accessible, though.
The spur and sector gear are on 8mm steel bushings, while the bevel gear sits on a steel bearing of the same diameter. A quick test of the gears reveals the shimming to be somewhat lacking. The bevel gear has noticeable play, as does the sector gear. The spur is the only properly shimmed gear and, unlike the other two, has been shimmed exceptionally well. Checking the inside, you can see that attempts at shimming have been made, as there is a varying number of shim plates on each gear, but the end result does leave a lot to be hoped for.
The quick change spring guide is plastic, the spring a linear one. The piston has a full length metal tooth rack, and all gears are steel. The lubrication inside the gearbox is very minimalistic. The nozzle comes without an o-ring.
The thing that makes the gun feel so nice to fire is the trigger and micro switch combination. However, the trigger parts seem proprietary, which may give you headaches in the future in case you need to replace them.
Conclusion
The Nuprol Delta AK-21 is an interesting and, at current, unique AR style AEG. The externals are good, and firing feels crisp and closes on authentic. Sadly, the gun is plagued by a number of quality control issues and low power out of the box. Magazine compatibility also leaves something to be hoped for, and the replica’s exterior design does not match the original on the lower receiver. I personally wanted to like this rifle, but with the issues it has, I can’t suggest purchasing one unless you know how to rectify the problems you may likely end up facing.
