Pistol Caliber Billet Upper

Rated 5.00 out of 5 based on 2 customer ratings


  • Manufacturer: New Frontier Armory
  • Model: Pistol Caliber Billet AR-9 “Slick Side” Upper with LRBHO
  • Caliber: Multi
  • -Dealer Price will appear in cart when logged in

Out of stock - Join the waitlist to be emailed when this product becomes available

SKU: PCUPPER Categories: ,


Pistol Caliber Billet AR-9/45 “Slick Side” Upper with LRBHO (Last Round Bolt Hold Open)

 Manufacturer: New Frontier Armory

Model: Pistol Caliber Billet AR-9/45 “Slick Side” Upper with LRBHO — PATENT PENDING

Caliber: Multi (will accept any barrels, bolts and caliber designed for the AR-9/45 style platform)

Weight: 8.96 oz

Measurements:  7.662″ x 1.375″ x 2.314″

 Other Specifications and Features of the Billet AR-9/45 “Slick Side” Upper with LRBHO:

  • Machined from 7075 T6 aircraft grade billet aluminum
  • Matte black hard-coat anodized per Mil 8625 Type 3 Class 2
  • Compatible with all standard AR-15 / AR-9 components and most aftermarket parts
  • Manufactured to MILSPEC on state of the art CNC equipment for consistent quality parts and exacting tolerances
  • Save money by building your own AR-9 rifle or pistol from the ground up exactly the way you want it configured
  • Designed to match lines with New Frontier Armory C-9  & C-45 Billet Lower
  • Contains integrated Last Round Bolt Hold Open (LRBHO) technology (PATENT PENDING) that reliably holds the bolt open when magazine is empty
  • LRBHO feature is designed for lowers that accept Glock style magazines
  • **NOTE — This upper is not machined for a gas tube as it is intended for blowback gas systems only


Once assembled the small “hook” end of the wire form in the upper should be pushed up by the follower of an empty Glock magazine which will engage the bolt catch on the last round fired to hold the bolt in the locked position.  If it does not engage, or engages before the last round is fired you can make VERY SMALL adjustments by SLIGHTLY bending the “hook” end down to lock faster or up to lock slower.  They are set and function checked during assembly with brand new Glock magazines and our standard bolt catches.  Because of varying magazine specs, magazine specs changing over the life of the product, different thicknesses of the pad on the bolt catch and other variables, this adjustment may be necessary with your specific parts.

**NOTE:  Some rail systems that use anti-rotation tabs may need slight modification to fit this upper.  It is designed for flush mounting rails and standard hand guards.

The New Frontier Armory Pistol Caliber Billet AR-9/45 “Slick Side” Upper with LRBHO is proudly MADE IN THE USA by hard working American men and women.

Additional information

Weight .72 lbs
Dimensions 9.75 × 3.5 × 3.5 in

Questions and answers of the customers

  1. 0 votes
    Answered by the admin

    The C5 upper has special cuts to allow for the larger MP5 magazine to be inserted.   The PC Upper has the LRBHO feature that works with only Glock Magazines.

  2. 0 votes
    Answered by the admin


  3. 0 votes
    Answered by the admin

    No, when using the proper buffer weights your brass will eject at an angle that will miss you.

  4. 0 votes
    Answered by the admin

    Yes, both this standard charging upper (PC-UPPER) and (PC-NRSC) Side Charging Uppers are both good choices for the C-45 Lowers.

  5. 0 votes
    Answered by the admin

    It doesn't have a purpose towards function, they're designed and machined with this groove for aesthetic reasons and to lighten the overall weight of the upper.

Send me a notification for each new answer.

You may also like…

Service Disabled Veteran Owned Small Business Authorize.net