Gibbz Arms G4 Side Charging AR15 Uppers Review

Gibbz Arms G4 Side Charging AR15 Uppers Review Why the Gibbz Arms G4 Side Charging AR15 Upper? We love the AR15 platform for a variety of reasons, not the least […]

Gibbz Arms G4 Side Charging AR15 Uppers Review

GibbzArms G4 side charge upper review Lucid Optics M7 Newtown Firearms Bear Creek Arsenal R&J Firearms UniqueARs - Bob shooting

Bob shooting the Gibbz G4 upper right hand build

Why the Gibbz Arms G4 Side Charging AR15 Upper?

We love the AR15 platform for a variety of reasons, not the least of which is that it is like Legos for adults. The number of options that one can mix and match to make an AR-15 “just right” is mind boggling.

However, there are two major design issues:

  1. Charging handle:
    This has bothered me since I first held an M-16 many (many, many…) moons ago when I still wore the uniform of the US Air Force… the charging handle position requires the operator to break cheek weld and reposition the rifle in order to cycle the bolt. In recent years I have seen a variety of approaches to correcting Eugene Stoner’s ergonomic faux pas, but none that grabbed my attention quite as abruptly as the patent pending G4 Side Charging upper system developed by Gibbz Arms.
  2. Right handed:
    As a right handed shooter I never gave a second thought to the fact that the AR15/M-16 platform is made for a right handed shooter. I mean, why would this bother me? In short, it doesn’t. However, Senior Writer Josejuan is left handed. EVERY single gun we look at elicits a heartfelt and detailed analysis of exactly how bad the design is for southpaws. If for no other reason than to stop my ears from bleeding, I have found myself inexplicably interested in left handed ARs.
GibbzArms G4 side charge upper review Lucid Optics M7 Newtown Firearms Bear Creek Arsenal R&J Firearms UniqueARs - stock photo: G4 side charge upper and cam pin

Found by chance

Imagine my surprise when I stumbled on a photo of a side charging AR15 and tracked it back to the Gibbz Arms website. Not only has Gibbz Arms corrected Stoner’s ergonomic oversight by moving the AR-15 charging handle from the rear centerline of the receiver to the front of the side of the receiver, but they also offer their creation in a left handed version. They call it the G4 Side Charging upper and it could spell double trouble for other AR manufacturers. Gibbz Arms was kind enough to send both a right and left handed side charging upper for use in a pair of Franken-builds taking shape in the Gear Report testing lab.

To reciprocate, or not reciprocate? THAT is the question

Moving the charging handle to the side of the AR15 solves much of the issue of the original charging handle design. However, I have seen a couple of different approaches to implementation.

Reciprocating ejector slot charging handle:

The most straight forward is simply adding a slot to a slick-side upper receiver extending just aft of the ejection port, then through this slot adding a small, rigid handle to the bolt. While simple, this solution adds an exposed, reciprocating handle on the ejector side. While I can envision operation of a side charge handle of this type without incident, I also know that if there is a way to hurt myself on this type of handle, I will find it. The charging handle is operated with the trigger hand.

Bear Creek Arsenal side charging ar15 upper receiver

Reciprocating ejector port side charging AR15 upper receiver from Bear Creek Arsenal

Bear Creek Arsenal side charging ar15 upper receiver

BCA side charge upper: bolt partially retracted

Reciprocating non-ejector slot charging handle:

Similar to the ejector slot charging handle, but on the opposite side. Again, the exposed handle extends through a slot in the upper receiver and into the bolt. As the rifle is fired the charging handle moves forward and aft with the bolt. Again, it may operate quite nicely, but I suspect I would fairly rapidly find a way to hurt myself on the reciprocating handle. The charging handle is operated with the non-trigger hand.

10-JP_Enterprises_GibbzArms_ohuhu_pro_mag_Bear_Creek_Arsenal (17)Non-reciprocating, non-ejector side charging handle:

Unlike the prior two, this charging handle does NOT move every time the bolt moves, as it is not installed in the bolt. The Gibbz Arms G4 Side Charging uppers make this work via any mil-spec AR-15/M-16 bolt carrier group (Gibbz says they haven’t found any AR-15/M-16 bolt carrier groups yet that won’t work with their uppers) with one little part swapped. Gibbz provides a modified bolt cam pin which extends vertically to interface with their charging handle. The charging handle is held at the forward end of the receiver by a detent as the bolt cycles during firing. Manually cycling the bolt is as simple as grabbing the handle with the non-trigger hand and pulling aft. The charging handle is mounted on a guide which rides in a horizontal channel on the non-ejector side of the upper, parallel to the bolt. With no charging handle at the rear of the upper receiver the operator can mount sights and/or optics that hang off the rear blocking the standard charging handle, like night vision optics.

Of these three types we have tried the Gibbz Arms G4 Side Charging uppers. We are open to testing the other types of side charge uppers, but have not yet received any.

39-JP_Enterprises_GibbzArms_ohuhu_pro_mag_Bear_Creek_Arsenal (47)

Left handed side charge ar15 upper from Gibbz Arms

Don’t get LEFT out…

As a right handed shooter I have never known the joy of getting smacked in the face with my own AR15 brass… until now. Since Gibbz Arms sent both right and left handed G4 Side Charging uppers I have had the rare opportunity to shoot the left handed upper and see how those who are left hand dominant live. I can attest to forgetting that the Gibbz Arms G4 Side Charging uppers do not have pronounced brass deflectors, so a right handed shooter can get brass directly back into their face (depending on how the gas system is configured).

To my credit, it only took a few rounds of hot brass off of my left cheek to convince me to hug the stock a bit tighter and take my face out of the path of flying brass. It was annoying, but it was temporary since all of my other rifles are either right or bottom eject. For left handed shooters however, this annoyance doesn’t go away. While I see a trip to most any gun store as presenting a huge number of options, I am becoming a bit more attuned to the frustration that Josejuan feels when I’m pawing over a wide variety of prospective new guns, and the store has only one left handed gun of any sort. The left handed version of the Gibbz Arms G4 Side Charging upper is a mirror image of the right handed upper. The only difference a left handed shooter needs to be aware of is that, like all left handed ARs, the left handed AR15 upper from Gibbz Arms uses a left handed bolt assembly. Not a whole left handed AR-15/M-16 bolt carrier group, just the bolt assembly itself. The bolt body, firing pin, etc are all standard.

UniqueARs GibbzArms G4 side charge upper review Lucid Optics M7 Newtown Firearms Bear Creek Arsenal R&J Firearms JP Enterprises - assembly

Assembling the Gibbz Arms G4 side charge upper builds

Variables, the spice of testing

We had a number of variables in our two AR15 upper receiver builds which added complexity and risk. First and foremost, Jeff and Josejuan completed these builds and neither had assembled an AR15 upper before. The risk of mistakes during assembly that would impact the upper’s performance was real. This build was also done using parts from a wide variety of manufacturers. We really like to test rifles and uppers that come assembled from the manufacturer so that we can eliminate the variables of mistakes in assembly and poorly selected or paired parts. However, we had acquired a pair of barrels for testing from our friends at Bear Creek Arsenal, hand guards from JP Enterprises and Unique ARs, a AR-15/M-16 bolt carrier group from NF Manufacturing (review), an adjustable gas block from JP Enterprises, (long live the Oxford comma!) and Muzzle brakes from R&J Firearms. We really didn’t want to tear apart any existing uppers to test all of those parts. New builds were in order.

UniqueARs GibbzArms G4 side charge upper review Lucid Optics M7 Newtown Firearms Bear Creek Arsenal R&J Firearms JP Enterprises - assembly handguard

Gibbz Arms G4 Side Charge upper, Right handed:

Gibbz Arms G4 Side Charge upper, Left handed:

*Video* Here is a quick look at both of our Gibbz G4 based builds and some dusk shooting we did shortly after completing the builds. Gotta love the fireballs shooting out of the R&J Firearms muzzle brakes!

GibbzArms G4 side charge upper review Ohuhu optic JP Enterprises Bear Creek Arsenal R&J Firearms UniqueARs - Jeff shooting

Jeff testing a Hexmag in the Gibbz Arms left hand AR15 upper build

How we tested

The entire Gear Report team have shot both of the Gibbz Arms G4 Side Charging upper builds, most in a broad range of scenarios using various optics, ammunition types and other accessories (benches, bipods, slings, etc.) We shot them standing, sitting and prone, still and moving, with magnified and unmagnified optics, with heavy and light projectiles, in warm and cool weather, rain and shine, rapid and slow – controlled fire, and with numerous types of magazines. Our goal was to put these uppers through the wringer so we could evaluate each part in the builds and each of the completed builds as whole.

Manual of Arms and other differences

Given that each of the Gibbz Arms G4 Side Charging upper builds is a mix-master with parts from various sources and installed by well meaning, but inexperienced hands, we had modest expectations. Much to our surprise, once we got past the initial break-in each rifle has run very well. We look forward to testing complete Gibbz Arms rifles in the near future. Since this review is for the side charging uppers, lets focus on how they performed. They are much like standard AR15 upper receivers in how they function and feel while firing. The genius of the Gibbz Arms G4 Side Charging AR15 uppers is most evident when preparing to fire.  To illustrate, contrast operation of a standard AR-15 charging handle to the Gibbz Arms G4 Side Charging system. I typically hold the AR15 with my left hand on the handguard and the right on the grip, with index finger resting on the mag well and beside the trigger until ready to fire. We like to transport uppers with the bolt closed, then lock them open as we take them out of the case so that the clear chamber is easy to verify.

  • Standard charging handle equipped uppers:  For this I would slide my left hand back to cradle the front of the mag well and place my left thumb on the bottom of the bolt catch. I remove my right hand from the grip to the rear of upper receiver, with my index and middle fingers straddling the charging handle. The buttstock rests in the pocket of my right shoulder. I pull the charging handle fully aft and make sure the bolt catch holds the bolt aft.
  • GibbzArms G4 side charge upper review Lucid Optics M7 Newtown Firearms Bear Creek Arsenal R&J Firearms UniqueARs - Jeff Charging

    Jeff demonstrating cycling the side charge lever on the Gibbz Arms side charging upper

    Gibbz Arms G4 Side Charging uppersMy right hand remains in place on the grip, with trigger finger extended to the mag well beside the trigger and the buttstock rests in the pocket of my right shoulder throughout this operation. My left hand comes back to push the side charging handle aft. When approaching full aft I extend my left thumb down to actuate the bolt catch.

Better ergonomics

It is easy to see that there are less movements required to operate the Gibbz Arms G4 Side Charging AR15 uppers, and those movements only involve the left hand. There is no awkward removing the trigger hand from the pistol grip or pulling the rifle away from the body to accommodate the full range of motion of the standard AR-15 charging handle. Perhaps a better illustration would involve a malfunction like a Failure To Eject/stovepiped spent casing while shooting. With a side charge upper the operator can maintain cheek weld and trigger hand on the pistol grip while rotating the rifle slightly to the non-ejection port side to give a clear view of the ejection port, while cycling the charging handle with the left hand. When the FTE is cleared the operator is already in position to resume firing immediately. Even if a non-side charging AR15 is equipped with an upgraded charging handle that allows charging with the left hand, they still have to break cheek weld since the charging handle travels back over the buffer tube and stock… into the face of the operator.

GibbzArms G4 side charge upper review Lucid Optics M7 Newtown Firearms Bear Creek Arsenal R&J Firearms UniqueARs - gas key door

This is the Gas Key door

Two other things I noticed about the Gibbz Arms G4 Side Charging AR15 uppers are:

  • The lack of a standard brass deflector can result in brass being thrown back at an angle not normally seen on ARs, depending on how the gas system is adjusted and what ammo is used.
    *Update: Gibbz Arms is offering new side charge uppers with both a brass deflector and forward assist starting in early-mid 2017.
  • With no standard AR-15 charging handle there is an opening at the rear of the upper receiver. It is needed to allow the gas key to pass in/out of the upper receiver when the bolt is removed or installed. Gibbz has installed a little pivoting gas key door to cover the hole and prevent a rush of hot gasses in the shooter’s face every time the rifle is fired. Any time the upper is removed from the lower or pivoted forward away from the lower you must remember to tuck the little door back in place as you pivot the upper back into place and secure the rear take-down pin. The gas key door is held closed by the top of the lower receiver buffer tube. We are told that the door seals better than a standard AR-15 charging handle, sealing gasses in the receiver better when shooting suppressed. We hoped the ATF would approve any of our various silencers by now so we could test this, but we are still waiting.

I don’t consider either of those “issues”, just differences.

How they worked

GibbzArms G4 side charge upper review Lucid Optics M7 Newtown Firearms Bear Creek Arsenal R&J Firearms UniqueARs - Jeff shooting

Brass whizzing past Jeff’s head

Although these Franken-builds are comprised of a wide variety of parts we have had no issues with fit or parts compatibility. Given that the Gibbz Arms G4 Side Charging AR15 uppers are machined from billet instead of forged, we expected good tolerances throughout. We have installed these uppers on lowers from JP Enterprises, Anderson Manufacturing, SOG Armory and WMD guns and found good fit in all cases. Initially it appeared that both builds had cycling/feed issues, but this went away after about 20 rounds, swapping out the new mags for proven mags and tuning of the JP Enterprises adjustable gas block on the left handed build. It should also be noted that installation of the Gibbz Arms G4 Side Charging AR15 uppers did not require a full Upper Receiver Parts Kit. Since there are no forward assist or dust cover those parts aren’t needed. No need to buy a standard charging handle either.

Anything we don’t like?

One minor and one that I can’t decide how important it is.


The location of the side charging handle means that the shooter’s hand must travel down the side of the upper receiver whenever the bolt is cycled. The way I have always mounted some optics puts bits in the path of my hand while cycling the charging handle. In my case it is usually just the ends of rail clamp screws or QD levers, either of which can be reconfigured to sit on the other side of the rail, leaving the charging handle side clear. Just be aware of this as you set up your optics and you will likely be able to position any protrusions on the ejector side of the receiver. With 15 slots on the full length top picatinny rail you will have plenty of options if your top mounted accessories need to be repositioned. Alternately, you might just want to hold your charging hand a bit further away from the receiver. The handle itself is solid and stout, so you don’t need the additional leverage of holding close to the receiver. This is not a deal breaker for me at all and is cancelled out by the fact that the standard charging handle is often hidden and hard to reach under my magnified optics.


Most people shoot clean factory ammo in a clean rifle in good conditions, so they never need to use the forward assist. I was trained to bump the forward assist if there is any question whether the bolt made it fully into battery, and often shoot reloaded ammunition and/or shoot in less than ideal conditions… any of which can lead to a slightly out of battery condition that may be rectified by employing the forward assist. So, I’ve found myself on a couple of occasions reaching for the forward assist that isn’t there on the Gibbz Arms G4 Side Charging AR15 uppers. If forward assist is a big deal to you, then this could be a deal breaker. If you are one of the many people that has never found the forward assist on an AR-15 to be remotely useful, then it may be a good thing that it is not present on the Gibbz Arms G4 uppers. You decide.


Gibbz also lists these warnings on their site. I had no issues with either, so I wouldn’t call them “dislikes”, but they could be important to some readers:

“* Upper not compatible with hand guards with anti-rotation tabs without modification *

IMPORTANT!! You must use the G4 Enhanced Cam Pin in the G4 Side Charging Uppers!
Use of the Standard Cam Pin will cause the Bolt Carrier Group to lock up in the G4 Upper Receiver and be VERY difficult to remove and possibly damage the Upper Receiver.”

I believe that the handguard anti-rotation tabs can simply be filed off to make the handguard fit, but don’t have a spare handguard to verify this.
And the G4 Enhanced Cam Pin is provided with the upper, so this is not a big deal… unless, like us, you swap bolts a lot in your AR15s. If so, then you will have to pay attention to be sure that you ONLY put install a bolt in your G4 upper if the G4 Cam Pin is installed. Swapping between the standard and G4 Cam Pin takes me about 2 minutes.

UniqueARs GibbzArms G4 side charge upper review Lucid Optics M7 Newtown Firearms Bear Creek Arsenal R&J FirearmsAesthetics

I consider it a bonus that the Gibbz Arms G4 Side Charging AR15 uppers look different than other AR15s. I wouldn’t buy one just for the different look, but I have no problems with the many folks that would. The lines of the G4 are clean and modern. Heck, I might even be tempted to call the Gibbz G4 uppers sexy.


Gibbz Arms G4 Side Charging uppers

Gear Score
The Gibbz Arms G4 side charging upper impressed us with craftsmanship, innovation and functionality. We recommend the G4 as a great option. July 2016 Update... upgrading to 4.5 based on a LOT of really hard use as one of our primary testbed uppers. The Gibbz G4 keeps taking the abuse and performing flawlessly. Feb 2017 update... still going strong!

About Jeff

Jeff is the Editor in Chief of Gear Report and a National Shooting Sports Foundation Media member. He reports on the outdoor industry, reviews gear for camping, hiking, shooting, hunting, paddling, backpacking and other active pursuits. A USAF veteran, Jeff earned a MBA in Marketing and Health Services. He specializes in consultative selling and internet marketing. As the VP of BD & Marketing, Jeff provides sales and marketing leadership to MGECOM, Inc. and helps acquire new clients in need of solutions for online merchants in need of Affiliate Marketing program management. Jeff founded and manages Cress Sales & Marketing LLC, offering online sales and marketing consulting and services to online merchants and service providers.