ARCTURUS M4/AR-15 SPR Rifle AT-AR01-RF AEG

If you have a long range leaning, or you have an armoury full of short weapons and fancy something with a bit more poke at a distance, the ARCTURUS M4/AR-15 SPR is well equipped for the role. On the outside, we have a nice long 17.5-inch outer barrel, 15-inch M-LOK handguard and full metal externals with steel controls, and inside we are treated to a 6.03mm steel tightbore inner barrel, rotary HOP-up unit, quick change spring system and a smattering of low friction parts, as well as a Teflon sealed air nozzle.

For use as a Special Purpose Rifle (SPR), the M4/AR-15 SPR is already there with its above average accuracy and consistency, just pop a scope on! For a true DMR, there is more work to be put in, but this is far less than other comparable platforms due to the choice of pre-upgraded internals focussing on air seal and reducing friction.

At the tip of the 17.5-inch outer barrel, we can find a four-prong muzzle brake style flash hider, providing an aggressive but dynamic look to the front end of the SPR. A muzzle brake is the perfect device for a real world SPR, providing reduced recoil which is essential for a precision setup. If you prefer a different muzzle device, or you want to mount a tracer unit or suppressor this is easily done by removing the grub screw on the bottom of the muzzle brake and unscrewing it, revealing common 14mm CCW male barrel threading beneath.

The barrel profile of the M4/AR-15 SPR is a straight heavy style barrel, giving it the appropriate looks for a real world SPR, rather than simply adding an extension to the standard M4A1 barrel. This shows ARCTURUS pay attention to the small details and is willing to go the extra mile for realism. There is also a dummy gas block and gas tube which runs back to the receiver, visible through the handguard ports, making for a realistic build with nothing left out!

Moving rearwards we come to the handguard of the M4/AR-15 SPR which provides M-LOK negative space attachment slots at the 3, 6, and 9 o'clock positions, punctuated by weight reducing ports. The 12 o'clock position features a 20mm Picatinny rail with numbered slots so you can remount your optic in the same spot every time with ease. This means you can add the aperture iron sights included in the box, an optical sight and a PEQ laser unit with space to spare on this super long top rail. If the top rail isn't enough room for you, the M-LOK slots at the sides and bottom can be used to directly mount M-LOK accessories but can also be used to mount 20mm Picatinny accessories using M-LOK to Picatinny rail adapters.

The receiver is of a standard M4/AR-15 layout, with the fire selector on the left side of the lower receiver, magazine release on the right side of the magazine well, charging handle at the top rear of the upper and the bolt release catch being located dead centre on the left side.

The fire selector provides 3 modes of fire; safe, semi-auto and full auto with a 90-degree throw between each mode. This means you can change modes quickly, with little chance of sweeping past the mode you want when pumped with adrenaline. The magazine release sits well within reach of the trigger finger when in a firing grip, and can be also be used by left-handed shooters by pressing the catch with your weak side thumb. The controls on the ARCTURUS M4/AR-15 SPR are all steel, guaranteeing precise engagement for a full lifetime of use, and are treated to reduce corrosion so you should not need to oil them to keep rust away (don't keep your guns in the damp garage/basement regardless, just in case you didn't already know!).

When pulled, the charging handle will open the dust cover on the right side of the rifle and retract the steel mock bolt carrier, revealing the rotary adjuster of the HOP-up unit. The use of a rotary unit means you have one less thing to upgrade for DMR duty as it is the best design out there for the M4/AR-15, benefitting from improved setting retention and being able to be adjusted in finer increments. With your HOP-up adjustment complete, you can hit the bolt catch on the centre left of the receiver to return the bolt to the forward position with a satisfying metal-on-metal "clank".

The pistol grip of the M4/AR-15 SPR is the M4A1/M16A2 style finger ridged grip which features diamond checkering on either side, as well as linear grooves at the rear to promote positive grip in all weather. The grip is constructed from high density textured polymer and feels rock solid in the hand. The use of a high density polymer means no matter how much you hold this grip it will not become shiny over time like standard plastic grips often do. The trigger guard is a standard M4/AR-15 flat style guard, but this can be swapped for alternative AEG compatible trigger guards if you have the skills and patience to do it.

At the rear of the receiver, we also have an ambidextrous sling plate which mounts between the receiver itself and the 6-position M4/AR-15 buffer tube. The sling plate is constructed from steel and can be used with a single-point sling, or paired with a front sling point (available separately) to mount a two-point sling for extra control when the rifle is stowed and you are working the enemy over with your sidearm. The buffer tube allows any M4/AR-15 AEG stock to be mounted, and also functions as the battery compartment of the M4/AR-15 SPR.

To access the battery compartment you will need to remove the stock, which is slightly more difficult than a standard crane stock but provides plenty of benefits to balance the extra effort needed. To remove the stock you will need to hold the adjustment lever down, allowing the adjustment pin to protrude at the bottom. With the adjustment pin poking out you will see a hole through it, we suggest inserting an Allen key through this hole to get extra leverage in order to pull the pin out, and slide the stock off to the rear. With the stock removed you can then unscrew the battery cap on the rear of the buffer tube, revealing the Deans connector inside. For the ARCTURUS M4/AR-15 SPR we recommend a 7.4V 1300mAh LiPo battery in stick configuration.

The stock itself is a unique ARCTURUS design boasting a low profile adjustment lever protected from snags by the A-frame design of the stock, a QD sling socket on either side and a hinged butt plate which allows faster access to the battery compartment when the threaded battery cap of the buffer tube has been removed. To hinge the stock open you will need to turn the dial on the rubber butt plate by 90-degrees, after which the butt plate can be opened. This is a nifty feature, and makes up for the hassle of getting the stock off. If you carry out the process described in the previous paragraph but leave the battery cap out, you can change your battery far more quickly using the hinged butt plate of the stock.

As with other ARCTURUS offerings, the M4/AR-15 SPR is equipped with a rock solid internal feature set with some well chosen upgrade parts and nothing overly complex which may go wrong. The gearbox is a version 2 reinforced type with a quick change spring guide mounted on ball bearings for reduced rotational stress, and the piston head is also fitted with ball bearings, resulting in a long lasting and low stress gearbox setup.

The nozzle is Teflon sealed for superb air seal qualities, and the steel gearset runs on 8mm steel bushings for a smooth gearbox sound and unlaboured functionality. All of the wiring is heavy gauge low resistance wiring, making for a setup which is far more efficient in both air seal and power use than most of its rivals. This superb feature set is enhanced by the microswitch trigger, which provides a snappy trigger response in semi-auto, and genuinely feels like it must have a MOSFET inside. It doesn't, but it looks like ARCTURUS has proved you don't need a MOSFET for a rapid response if your gearbox is well built!

So, if you are in the market for a long M4/AR-15 platform the ARCTURUS M4/AR-15 SPR is certainly worth a look! The upgrade parts present inside, coupled with the long barrel and handguard make this a great long ranged tool, whether you are leaving it as it is and enjoying above average accuracy with full auto still intact, or you are taking it down the DMR route with higher FPS and semi auto locked off. Another DMR base gun contender, and one of the best out there currently!

Features

• Full metal construction
• 6.03mm Steel tightbore inner barrel
• Rotary HOP-up unit - The most recent M4/AR-15 design
• Microswitch trigger - Super snappy response in semi auto
• 14mm CCW male threaded outer barrel - Ready for a tracer or suppressor
• 20mm Picatinny railed receiver - Seamless integration with the handguard rail
• 17.5-inch Outer barrel - Ideal SPR/DMR length
• 15-inch M-LOK handguard - Loads of room for optics and accessories
• Finger ridged "A2" pistol grip with diamond checkering
• 6 Position M4/AR-15 buffer tube - Compatible with aftermarket M4/AR-15 AEG stocks
• Mil-spec curved trigger - Perfect for military style builds
• Slimline stock with QD socket - Reduced bulk, increased agility
• Ambidextrous steel sling plate - Ideal for single-point slings
• Bearing spring guide and piston head - Reduced rotational force, less friction
• Rotary adjustable HOP-up unit - Fine increments of adjustment, holds setting well
• Teflon sealed air nozzle - Great compression/air seal qualities
• Microswitch trigger - Snappy trigger response
• Low resistance wiring - Great electrical efficiency
• 8mm Steel bushings - Smooth running gearbox
• Compatible with M4/AR-15 AEG magazines

Package Includes

• ARCTURUS M4/AR-15 SPR Rifle AT-AR01-RF AEG
• 130rnd Medium capacity magazine
• Flip-up iron sights
• Deans to mini-Tamiya adapter
• Cleaning/unjamming rod