C-45 Billet Lower

New Frontier Armory

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1.00 LBS
C-45 Lower
Pistol Cal
Black Ano or RAW (Media Blast Only)
Magazine Type:
Glock Style
7075 Billet Aluminum

C-45 Stripped Billet Lower Receiver -- Glock Style Mags


Other Specifications and Features of the C-45 Stripped AR-45 Lower Receiver:

  • Machined from 7075-T6 aircraft grade billet aluminum
  • Choose from Matte black hard-coat anodized per Mil 8625 Type 3 Class 2, or RAW (Media Blast Only)
  • 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
  • Caliber marking of "Multi" so it can be used with different pistol caliber uppers
  • Compatible with most standard AR-15 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 are included
  • 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-45 rifle from the ground up exactly the way you want it configured and shoot for less!


  • *Due to the force exerted on the BCG with a blow back system, there is a high likely hood of breaking the bolt catch when activated by the LRBHO feature. New Frontier Armory is not responsible for sending replacements as this is not a warranty issue.


**NOTE – Please read the FAQ below regarding adjustment of your ejector before use and ensure you re-assemble with Loctite or similar threadlocker to prevent screws from backing out over time.



QUESTION: Do I need to adjust my ejector?

ANSWER: Yes, before firing your new pistol caliber lower we suggest you adjust your ejector. Loosen the two screws holding the ejector in to where it becomes a semi-tight 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 theleft side of the ejector(shooters left). At this point you should remove one screw at a time without disturbing the ejector location and add locktite to the screws and tighten them back down. This will ensure the screws will not back out over time.

QUESTION: What type of magazines will fit in this lower?

ANSWER: The lower was designed to fit and drop free factory Glock  pistol magazines. It has also been thoroughly tested with Magpul .45cal pistol magazines to fit and drop free. Although it accepts and shoots other aftermarket magazines (Promag, KCI, Kahn, etc) 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 Glock factory specifications.

QUESTION: What bolt carrier group will work with a Glock magazine fed AR-45?

ANSWER: You will need an AR-45 Bolt Carrier Group that has relief cuts to clear the Glock style magazines. The AR-45 BCG that we sell will work in both Glock style AR-45s as well as traditional Colt style AR-45s. We can also modify your Colt style AR-45 BCG for you to work properly with both systems.

QUESTION: What LPK will work with this lower?

ANSWER: Although we sell a specific LPK with just the parts needed to build the C-45 lower receiver, 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-45?

ANSWER: It is advised that you use an 8 oz or heavier buffer. Lighter buffers aren't safe to use in a blowback system with larger calibers such as the .45ACP and 10mm, and they may not feed some types of ammunition reliably without the added weight.

The New Frontier Armory C-45 Stripped Billet AR-45 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! You will be prompted at 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.

Weight: 1.00 LBS
Dimensions: 9.50 x 4.50 x 2.25 in

2 Reviews Hide Reviews Show Reviews

  • 5
    45/10mm lower

    Posted by Brice on 15th Apr 2024

    Honestly wasn't looking for a dedicated lower for the 10mm upper that I picked up from New Frontier but, the Easter sale sealed the deal. I have several of 9mm/40s&w lowers and the quality of them have been great. This matched perfectly with their complete 10mm upper.

  • 5
    C-45 LOWER

    Posted by Markus david on 21st Jun 2023

    Great lower planning to build another one

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