New Frontier Armory’s (NFA) C-5 ARs are not just another Colt clone. These guns run MP5 magazines. The big advantage to this is that the MP5 magazines are a true double stack magazine, feeding from both sides. This makes them run great in AR carbines and rifles.

I have been working with Pistol Caliber Carbines (PCC) since the Colt SMG. The Colt magazines were hard to load and prone to failures. I have always liked being able to shoot economically and train on pistol rated steel targets. PCCs have gotten steadily better over the years and I think the C-5 may represent the pinnacle of their evolution.

The C-5 looks just looks better than its Glock magazine fed cousins. Submachinegun magazines just look right coming out of an AR. You can buy the lower with a matched upper. They even sell an 80% version for a complete build project.

The C-5 lower was designed to fit and drop free factory MP5 9mm magazines.  NFA offers KCI MP5 9mm 30-Round Magazines on their site for  $34.99 Although it accepts and shoots KCI aftermarket magazines, New Frontier warns that some slight modification may be needed to get some aftermarket magazines to drop free because of the width measurements can vary from H&K MP5 factory specifications.

Building your own gun lets you save money by building your own AR-9 rifle from the ground up exactly the way you want it configured. The NFA lower parts kit is matched to this lower; no extra parts.

I have been looking forward to this product. New Frontier has a great reputation and I fully expect the C-5 is going to be a great gun. I bought everything from NFA. Because 9mm is well suited for short barrels, I decided to build a pistol. Starting with a matched a matched C-5 upper and lower, a pistol caliber lower parts kit and a complete Shockwave arm brace.

The lower has some premium features. The finish is a beautiful anodized matte black hard-coat. The rear take down pin detent hole is threaded so you can capture the spring when installing or removing the buffer tube.  The bolt catch pin is threaded so you don’t have to install that awkward roll pin.

I opted for a custom serial number and selector markings. I decided to continue New Frontier’s Star Trek theme. Don’t judge, you can pick your own serial number.

Best 9mm AR Build Ever: New Frontier Armory's C-5 AR Lower Uses MP5 Magazines
New Frontier Armory’s C-5 AR Lower with an MP5 Magazine

C-5 Billet Lower $169.99

  • Manufacturer: New Frontier Armory
  • Model: Stripped C-5 Billet Lower (MP5 Mag) – Anodized – Packaged w/ Hardware
  • Caliber: 9mm

Stripped C-5 Billet Lower (MP5 Mag) – Anodized – Packaged w/ Hardware

Manufacturer: New Frontier Armory

Model: C-5

Material:  Milled from 7075 T6 aircraft grade aluminum billets

Caliber:  9MM

Magazine:  MP5

Weight:  0.75 pounds

C-5 Lower Billet

Best 9mm AR Build Ever: New Frontier Armory's C-5 AR Lower Uses MP5 Magazines
The bolt catch pin is threaded and provided. No roll pin needed!

 Other Specifications and Features of the C-5 Billet Lower (MP5 Mag):

  • Machined from 7075-T6 aircraft grade billet aluminum
  • Matte black hard-coat anodized per Mil 8625 Type 3 Class 2
  • Precision machined magazine well with beveled feed lip for easy mag swaps
  • Machined and engraved to be compatible with 45 and 60-degree short throw fire control selectors such as the BAD_ASS ST 45 Lever
  • Compatible with most standard AR-9 components  and most aftermarket parts
  • Take down pin spring and detent hole is threaded for a 6-32 set screw for easy capturing (hardware included)
  • Upper tension screw behind grip screw (threaded hole with hardware included) to adjust any “slop” out of vertical fit between upper and lower
  • Ambidextrous trigger finger rests with grooves (above and below mag release/mag catch)
  • Threaded bolt catch pin (Threaded hole and hardware)
  • Integrated large opening “winter” trigger guard
  • Proprietary magazine catch assembly, feed ramp, and ejector is included and installed at the factory
  • Manufactured to MILSPEC (where applicable) on state of the art CNC equipment for consistent quality parts and exacting tolerances

Pistol caliber specific LPK is available HERE

Magazines can be found HERE

NFA sells three versions of C-5 Uppers  HERE.

If you don’t buy a C-5 compatable upper, no worries you can make widening cuts to accept the wider MP5 Magazines.

Pistol caliber specific LPK is available by HERE

Magazines can be found HERE