Rainier Arms AR-15 9MM Billet Receiver Set

Picture of a Rainier Arms AR-15 9MM Billet Receiver Set

Rainier Arms AR-15 9MM Billet Receiver Set

The Rainier Arms AR-15 9MM Billet Receiver Sets are CNC machined from solid billet 7075-T6 aluminum which is 70% stronger than the commonly used 6061 aluminum and finished with milspec hardcoat anodize to a surface hardness of 60 Rockwell. The precision machining of the Rainier Arms billets are well known in the industry. Rainier Arms AR-15 9MM Billet Receiver Sets utilize GLOCK® 9mm magazines.

Rainier Arms AR-15 9MM Billet Receiver Set Features

  • A4 Feed Ramps
  • 7075 Billet Aluminum
  • Upper and Lower are proprietary
  • Mil Spec Hardcoat Anodize
  • Threaded bolt catch screw
  • Threaded retainer screw for take down pin
  • Ambidextrous Bolt Release
  • Flared magwell
  • Compatible with short throw safety selector
  • Tensioning screw for proper upper and lower fit
  • Zinc-plated extractor and last round hold open lever
  • Last round bolt hold open on an empty magazine
  • Lower receiver accepts 9mm, .40 S&W and .357 SIG GLOCK® magazines
  • Slick side upper receiver with appropriately sized ejection port and no forward assist or dust cover
  • Accepts aftermarket Glock® 9mm double stack magazines. We recommend using factory Glock® magazines
  • Weight – Upper receiver 7.7oz Lower receiver 12.4 oz


Stern Defense AR-15 9MM Conversion Adapter

Picture of a Stern Defense AR-15 9MM Conversion Adapter

Stern Defense AR-15 9MM Conversion Adapter

There’s no need to go with a pistol-caliber specific AR lower on your next pistol-caliber carbine build. With the Stern Defense AR-15 9mm Conversion Adapter you have the ability to utilize popular pistol magazines which you may already have a supply of.

Stern Defense make two differ models of their Conversion Adapter, one which uses Glock® magazines, and one which uses either Smith & Wesson M&P or Sig 320/250 magazines.

The Stern Defense AR-15 9mm Conversion Adapter is easily installed into any mil-spec AR-15 lower receiver within seconds and even incorporates a last-round bolt hold open feature. Each adapter is machined from aluminum and requires the use of a 9mm/.40 S&W barrel and a Glock-cut bolt.

  • Made of aircraft grade aluminum
  • Lightweight, ergonomic design
  • Installs in seconds


  • The MAG-AD9 will not function properly on mag wells with irregular contours, “3D skulls, waves, and other non mil-spec contours.” 
  • NOT recommended for non mil spec billet lowers. 
  • For the best experience, please use the MAG-AD9 with ar-15 and m16 mil-spec lower receivers.
  • The MAG-AD9 is designed to be used with ar-15 and m16 mil-spec upper receivers.
  • The MAG-AD9 system is not compatible with New Frontier, PSA Hybrid or Foxtrot Mike bolts. This is due to the lug which strips a round off of the magazine being .035 of an inch further from center-line as compared to other bolt systems. If you are looking to use these bolts with our system Stern Defense will provide bolt modification services with the purchase of a mag-ad9. More info HERE.
  • The MAG-AD9 system is not compatible with Olympic Arms Bolts, Barrels  and Uppers


New Frontier Armory C-45 AR-45 Stripped Billet Lower Receiver

Picture of a New Frontier Armory C-45 AR-45 Stripped Billet Lower Receiver

New Frontier Armory C-45 AR-45 Stripped Billet Lower Receiver

New Frontier Armory C-45 AR-45 Stripped Billet Lower Receiver Features and Specifications

  • 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
  • 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
  • Takedown 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-45 rifle from the ground up exactly the way you want it configured and shoot for less!

Frequently Asked Questions: Source New Frontier Armory

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 the left side of the ejector (shooters left).  At this point you should remove one screw at a time without disturbing the ejector location and add loctite 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 large frame pistol magazines.    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 Glock factory specifications.

QUESTION:   Do you offer a reliable last round / empty magazine bolt hold open (LRBHO) System for this lower?

ANSWER:  YES — After watching several companies try and fail to incorporate a RELIABLE last round bolt hold open (LRBHO) system into their lower receivers we decided to take a different approach and will be incorporating our LRBHO technology (PATENT PENDING) in our matching upper receivers.  After rigorous testing and hundreds of hours of research and development we feel that this is the best option for LRBHO on a Glock magazine AR style firearm.  Our upper will be compatible with other manufacturers lower receiver that either don’t have a LRBHO or you can scrap the non-working LRBHO out of your existing AR-45 Glock Mag lower and solve the issue of not having a 100% functioning LRBHO.  For more information on our matching Pistol Caliber Upper, please CLICK HERE.

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.  Our Standard .45 BCG can be found here.

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 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-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.

Visit New Frontier Armory


Stern Defense SD Mod 4 9mm AR-15 Upper Receiver

Picture of a Stern Defense SD Mod 4 9mm AR-15 Upper Receiver

Stern Defense SD Mod 4 9mm AR-15 Upper Receiver

I noticed the SD Mod 4 9mm AR-15 Upper Receiver on Brownells new product section so I spent a bit of time researching Stern Defense. I didn’t learn much. The only thing I was able to determine besides their contact information is that they are a pistol caliber AR-15 hardware manufacturer, and as regular visitors know we are big proponents of the platform. If anyone has feedback on the hardware or company please drop us a line!

The Stern Defense SD Mod 4 9mm Upper Receiver is a complete, ready to go, upper receiver solution for those looking to spend less time building and more time shooting.

The 4 inch, 1-10 twist, Melonite finish barrel, is free float in a 4in M-LOK handguard attached to a 7075-T6 forged aluminum receiver.
On the end of the barrel mounted on the ½-36 threads is a 1.75” long, 1.2” diameter blast can designed to direct the short barreled blast away from the shooter.

  • 4in barrel
  • 4in M-LOK Free Float handguard
  • Complete assembly with 9mm bolt and charging handle
  • ½-36 muzzle thread pitch
  • 1.75” long by 1.2” diameter blast can muzzle device
  • SD BU9 9mm Bolt
  • Cartridge: 9mm Nato

Included in the upper receiver is charging handle and the Stern Defense 9mm Bolt which is compatible with both Glock and Colt SMG magazines, has a Melonite finish, and is works in conjunction with the Law Tactical Folding Adapter. The Stern Defense SD Mod 4 9mm Upper Receiver is made in the U.S.A

Stern Defense 4 inch MLOK rail(Barrel nut, bolts etc.)
Stern Defense 4 inch 9mm barrel.
SD MBC 9MM Blast Can.
Stern Defense assembled upper receiver with dust cover and forward assist.
Stern Defense SD BU9 Glock cut bolt.
SD CH1 enhanced charging handle.


The free float MLOK handguard from Stern Defense offers excellent ergonomics while remaining lightweight and strong. This handguard is MLOK compatible to accept your favorite attachments. Features a secure clamp on mounting system that ensures that the handguard remains in place even under heavy abuse, sustained full auto fire, and shooting prone from a bipod. Machined from 6061 aircraft grade aluminum and hard-coat anodized for longevity and durability. These handguards also feature quick disconnect swivel holes.  Also Included,  Barrel Nut and Bolts.

  • 6061 aircraft grade aluminum.
  • Hard-coat anodized.
  • Sturdy construction.
  • Lightweight construction.
  • Length 4 inches.
  • Smallest inside diameter 1.435 inches.
  • Made in U.S.A.

9mm Barrel

Stern 9mm barrels are ideal for gun lovers who want to build their own custom dedicated 9mm AR15 upper group. Our barrels offer an advantage over the competition. Every stern defense barrel throat is machined deeper for a longer free bore to accommodate bullets with a longer ogive. We have found that some common defense rounds jam into the rifling before the round is fully chambered. Some of the barrels on the market do not accommodate this and will potentially result in nasty malfunctions, resulting in a round being stuck in the chamber requiring manual methods to clear the malfunction.

Note: Barrel comes with locating pin installed.

  • Barrel length is measured in overall length from breech to muzzle.
  • Caliber: 9mm.
  • Length: 4 Inches.
  • Made in the U.S.A.
  • Threaded .5-36.
  • 1:10 TWIST.
  • 4150 Chrome-moly steel.
  • Melonite coating.

9mm Receiver

Mil-Spec flat top upper receiver with Stern Defense laser engraved dust cover and forward assist. Machined from 7075-t6 aluminum and hard-coat anodized. Mil-spec dry film lube in the bore.

  • 7075-t6 aluminum
  •  Hard-coat anodized.
  •  Sturdy construction.
  •  Made in U.S.A.

9mm Charging Handle

Mil-spec charge handle for AR-15 rifles.  Laser engraved with Stern Defense logo.  Our latch is  Ergonomically designed and provides a positive grip and easy one hand manipulations while charging your weapon under stressful situations. Made from 6061 aircraft grade aluminum billet and hardcoat anodized.

  • Laser engraved.
  • 6061 aircraft grade aluminum billet
  • Hard coat anodized.
  • Sturdy Construction.
  • Made in U.S.A.

9mm Specific Bolt

Made with 8620 AISI steel and boasting a Mag-Phosphate finish, the Stern bolt fits into Mil-Spec and Glock-pattern upper receivers.  It functions with Colt SMG, Glock magazines and it’s fully compatible with standard AR15/M16 charging handles. Comes fully assembled with all sub-components installed, including firing pin/spring/retaining pin, extractor, and extractor spring.   Also included in bolt assembly is a proprietary center and roll pins.  Our 9mm bolts incorporate our new bolt design which caters to single stage triggers with short resets.  It also allows use with the JP silent captured spring. This bolt is compatible with the Law Tactical folding stock and the Echo trigger.

  •     Made in U.S.A.
  •     Constructed from 8620 AISI steel.
  •     Custom 4140 billet extractor providing superior ejection.
  •     Glock cut.
  •     Coating: Mag-Phosphate
  •     Weight: 15.5 OZ with weight 13.3 OZ without..
  •     9mm
  •     Compatible with single stage short reset triggers.
  •     Compatible with the Law Folding Tactical Stock
  •     Compatible with the Echo trigger.
  •     Compatible with the JP Silent capture spring

9mm Blast Can

Designed to direct muzzle blast away from shooters. Which is especially helpful on short barreled rifles and pistols. Machined from 6061 aircraft grade aluminum billet and hardcoat anodized, 1.75 inches long and 1.2 inches in diameter.

Note:  Comes with crush washer.

  • 6061 aircraft grade aluminum.
  • Hard-coat anodized.
  • Sturdy construction.
  • Lightweight construction.
  • Made in U.S.A.
  • 9mm
  • Threaded .5-36

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Gas Block Genie AR-15 Gas Block Alignment Tool

Gas Block Genie – Install An AR-15 Gas Block The Easy Way!

Just spotted this on Brownells. Interesting, inexpensive and reusable tool for proper gas block alignment. Proper gas block alignment is on of those tasks on an AR-15 that on the surface looks simple and theoretically is but the devil is in the details. The first mistake novices make is to butt the gas block against the shoulder, this is wrong. The gas block is required to allow space for a handguard delta ring. Installing the gas block up against the shoulder on the barrel will result in a partially obstructed gas block and an AR-15 that may not cycle properly. The next area of concern is having the gas block level and perfectly aligned with the gas port. If the gas block is canted slightly the gas port will be obstructed and this too will result in an AR-15 that will not cycle properly. Fortunately the Gas Block Genie is here to make getting your AR 15 gas block properly aligned a simple task.

The gas block genie is currently only available for .750 barrels but other barrel diameters are coming soon.

Gas Block Genie

Ever put together an AR build, only to find that your semi-auto cycling system just doesn’t cycle? Looks like that gas-block installation didn’t go as well as you thought it did. Avoid future frustration by adding the Two Two Three Innovations Gas Block Genie to your AR building kit.

Unlike other gas-block alignment tools on the market, the Two Two Three Innovations AR Gas Block Genie Gas Block Alignment Tool can be used again and again, as many times as you want, during your AR build. All it takes is three simple steps.

The type of gas block doesn’t even matter when using the Gas Block Genie. Whether you’re working with clamp-on designs, rail-block designs or micro-size options, the Gas Block Genie can handle it all!

Picture of a Gas Block Genie AR-15 Gas Block Alignment Tool

Gas Block Genie AR-15 Gas Block Alignment Tool


Gas Block Genie Gas Block Alignment Tool Instructions

The Gas Block Genie quickly and easily allows you to perfectly align the AR-15 or AR-10 gas block hole with the gas port in your barrel every time.

  1.    Squeeze the Genie slightly to install into the forward face of the gas block so that the hole in the Genie is centered on the gas block hole. It may be easier to remove the rearmost set screw to do this. Part of the Genie should be sticking out the front side of the gas block
  2.    Use a very fine point marker or scribe to make a mark on the Genie where the forward edge of the gas block is. Make a small mark on the gas block at the slot in the Genie to indicate the top center of the gas block. It may be helpful to use a black marker on a stainless surface and a silver marker on a black surface.
  3.    Remove the Genie from the gas block and snap onto the barrel so that the hole in the Genie is centered around the gas port in the barrel.
  4.    Transfer the mark you made in step 2 to the barrel through the slot in the Genie.
  5.    Remove the Genie and slide the gas block onto the barrel.  As the Gas block approaches the barrel’s gas port you will see the line on the barrel and the mark on the front face of the gas block.  Simply align the two and you are finished!  A perfectly aligned gas block!
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