C-5 Pistol Billet Lower Receiver — MP5 Mags
Manufacturer: New Frontier Armory
Model: C-5 Complete Pistol
Weight: 2.25 lbs
Other Specifications and Features of the C-5 Complete Pistol Lower Receiver:
- 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
- Includes factory installed MILSPEC Lower Parts Kit (LPK), Pistol tube kit, and Shockwave stabilizing brace — Ready to pin to your upper and shoot!
- 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 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
- Save money by building your own AR-9 rifle from the ground up exactly the way you want it configured and shoot for less!
- Magazines can be found HERE
You must use an upper that has widening cuts to accept the larger width MP5 Magazines — We sell three versions of C-5 Uppers that can be found HERE.
ETS magazines may require slight sanding to ensure proper fitment due to variations from factory H&K Magazines. We have yet to find any fitment issues with HK, Zenith, or KCI mags.
QUESTION: What type of magazines will fit in this lower?
ANSWER: The lower was designed to fit and drop free factory MP5 9mm magazines. It has also been thoroughly tested with many aftermarket magazines to fit and drop free. Although it accepts and shoots other aftermarket magazines some slight modification may be needed to get them to drop free from this lower because of the varying width measurement we have seen when checking these magazines to H&K MP5 factory specifications.
QUESTION: Do you offer a reliable last round / empty magazine bolt hold open (LRBHO) System for this lower?
ANSWER: NO, like the original MP5 platform, there is no LRBHO function. You must use either our C-5 Slick Side Upper or our C-5 Non-Reciprocating Side Charging upper as they are widened to accept the MP5 magazines. Other manufacturers make uppers cut for MP5 mags as well, but we can’t guarantee their compatibility at this time.
QUESTION: What bolt carrier group will work with a MP5 magazine fed AR-9?
ANSWER: Both AR-9 BCGs that we sell (CLICK HERE for AR-9 BCGs) will work in both MP5 Mage AR-9s as well as traditional Colt style AR-9s and Glock Mag AR-9s.
QUESTION: It seems as though my BCG may be hitting or rubbing the ejector on the lower, how can I fix that?
ANSWER: Loosen the two screws holding the ejector in to where its a friction fit. Ensure the ejector is seated all the way to the rear and all the way down in the pocket. Close your upper onto the lower with the bolt all the way forward. SLOWLY cycle the bolt in and out about 1/4 of the way back a few times then let the bolt close all the way and tighten the ejector screws. They are cupped to get a good grab on the SS ejector, so only hand tight or you risk the chance of bending the ejector over. Any slight rubbing at this point will wear in the ejector after a few magazines are cycled through the gun. If you see excessive rubbing you can also file down the top corner on the left side of the ejector (shooters left)
QUESTION: What LPK will work with this lower?
ANSWER: Although we sell a specific LPK with just the parts needed to build the C-5 lower receiver HERE, any standard AR-15 LPK will work. You will not need the magazine catch assembly, bolt catch roll pin, or trigger guard that are normally included with standard LPKs.
QUESTION: Do I need to use a special buffer when I build my AR-9?
ANSWER: Although its not technically required, it is advised that you either use a 9mm buffer (longer and heavier than carbine) or a spacer in your buffer tube before you place your spring in. The reason for this is to limit the BCG travel to the rear so it doesn’t come back forward and smash the bolt catch hard enough to break it. The 9mm BCG is shorter than a standard BCG. You can use a carbine buffer with a spacer (WHICH YOU CAN PURCHASE BY CLICKING HERE).
The New Frontier Armory C-5 Stripped Billet AR-9 lower receiver is proudly MADE IN THE USA by hard working American men and women.
This is a serialized item considered to be a firearm by BATFE. This item must be shipped to a Federal Firearm License (FFL) holder. All BATFE, GCA & NFA rules apply! This item must be shipped to a Federal Firearm License (FFL) holder. You will be prompted during checkout to pick an FFL to ship to in your area using our FFL Locate tool. YOU will be responsible for checking with your local FFL to ensure this weapon is legal in the state that you reside and that they will accept this weapon on your behalf and transfer it to you. New Frontier Armory, LLC will NOT be responsible for any shipping or admin charges incurred by packages not being accepted by the FFL you choose during checkout.