Best HK91/G3 Upgrades (Modernizing)

The HK91/G3 platform is slightly outdated, but let’s see if we can get it on par with modern AR-10 rifles.

So if you want to learn about the best HK91/G3 upgrades and accessories, keep reading.

This post will cover the best HK91/G3 upgrades and accessories, which will work on the PTR 91 and other clones. 

Why Upgrade the HK91/G3 Rifle?

Let’s start by saying the H&K G3 rifle is iconic. Some people grew up seeing these rifles in popular movies and fell in love with the platform.

We are lucky to purchase these rifles and clone variants much cheaper nowadays. The PTR is among the most affordable of these G3 clones. Parts are readily available, surplus magazines are cheap, and it’s built like a tank.

Most people see the appeal of the 308, and the G3 rifles are just cool. Out of the box, they are shootable, have a fixed stock, and have a slim profile handguard.

Problems With The HK91/G3

Some of the downsides are that the recoil is pretty heavy. There is no easy way to add an optic, and there is no weapon light.

1. Recoil

Roller-delayed blowback operation in the G3 platform necessitates using a large, heavy bolt that moves back and forth within the receiver, adding to the gun’s overall weight.

Additionally, the low iron sights on the gun require a sharp drop in the stock, further affecting the gun’s balance.

Compared to other guns of similar size, weight, and caliber that utilize different recoil systems or an inline stock, the G3 platform experiences significantly more recoil. The heavy bolt and off-axis recoil also contribute significantly to muzzle climb when firing.

While the recoil impulse of the gun is generally pleasant and not overly punishing, the gun does tend to push the shooter around during use.

2. Optics Mounting

Another issue with the gun is the steep drop in the stock, which makes it difficult to obtain a proper cheek weld when using an optic.

When an optic is mounted low on the gun, it results in an inconsistent chin weld, while a higher-mounted scope can force the shooter to adopt an uncomfortable neck weld.

3. Accessory Mounting

The standard furniture on the gun does not provide any means of mounting lights, lasers, grips, or switches.

Although aftermarket upgrades are available, they often encounter issues with the charging handle and the absence of a 12 o’clock rail section, resulting in clearance problems.

4. It’s Awkward

Despite investing significant resources, some issues cannot be resolved, and this is the case with the G3 platform’s battery of arms, which is unconventional.

Reloading a roller-delayed gun is not straightforward and differs from reloading other firearms.

The gun does not provide the convenience of a last-shot hold open or a bolt drop. Moreover, loading fully loaded magazines on a closed bolt is unreliable.

The best method for reloading is to lock the bolt back, remove the magazine, insert a new one, and then manually drop the bolt.

With roller guns, you only realize you’ve run out of ammunition when you pull the trigger, and nothing happens.

Unfortunately, reloading the G3 platform is a slow and cumbersome process that cannot be ignored.

5. It’s Heavy

The gun is inherently heavy, and replacing the lightweight plastic furniture with metal to improve the rifle’s capabilities adds more weight. As a result, aftermarket parts are ineffective in reducing the gun’s weight.

Before any upgrades are made, the G3 platform’s 18-inch stepped barrel weighs nine and a half pounds, more than 308 ARs with full-length free float rails.

To modernize the G3 rifle and address these issues, we need to find solutions that can help reduce weight while improving its capabilities.

If you’re still reading, it’s safe to assume that you’re on board with this plan, or you may be considering selling your G3 variant and purchasing an AR10 instead.

Best H&K G3 Upgrades

To improve the rifle’s performance, you’ll need a better bolt and spring system that reduces recoil and allows faster, more accurate follow-up shots.

You’ll also need a new stock to provide a better cheek weld when using an optic and a rail to mount the optic.

Choosing a suitable optic for the rifle is also crucial.

A new handguard with mounting points will allow you to add a weapon light and a laser if you’re using night vision.

Lastly, a trigger upgrade, sling, and extra magazines and ammo will complete the necessary upgrades.

Muzzle Brake / Suppressor

Because of the intense recoil of this rifle, the only option to tame the rifle is by adding a muzzle brake.

There are two options when getting a muzzle brake. The first option is to get an M15x1 RH muzzle brake. The second is to get an adapter to add a muzzle brake with a more common thread pitch.

The unfortunate thing about the M15x1 RH thread pitch is that it doesn’t support much for muzzle brakes, only flash hiders.

So honestly, the best muzzle brake for this gun is a suppressor. I know that isn’t an option for everyone but if possible to that route.

The Dead Air Armament Flash Hider will pair nicely with a suppressor and can be used for this setup. It is the proper thread pitch and not too expensive.

Click Here to check the current prices of the Dead Air Armament Flash Hider

The Chimera 300 is a good option for this setup. Its fully welded stainless steel tube and a mixture of Cobalt-6 and Inconel baffles give you all the strength you need without adding unnecessary weight.

Muzzle Average: 308 WIN: 136.6 dB

• Full auto rated
• Short barrel rated

Click Here to check the current prices of the Chimera 300

Stock

The Spuhr Stock Assembly is a good upgrade for the G3 and clones. What you get is similar to an AR stock. You get an AR buffer tube adapter, a carbine-style AR buffer tube, a sling attachment end plate, and a customer cheekpiece.

It has six positions and raises your cheek weld and head up higher. This will prevent you from using the iron sights, but you should use an optic anyway. (you can remove the cheek riser if you still want to use irons)

Optic & Rail

One of the most popular optics to modernize this rifle is the Aimpoint CompM4. This weapon sight is bombproof and very reliable.

I recommend removing the rifle’s rear sight and running this red dot. You can always add a magnifier or use night vision with this optic and do not want the irons getting in the way.

This optic setup is very similar to what I use on my AK47. If you want to see that setup check out my Best AK-47 Upgrades & Accessories (All Variants) article.

Trigger

Handguard

The most versatile handguard that will give you M-Lok mounting options is the AIM Sports HK91/G3 Handguard.

Weapon Light

You need a good weapon light for any serious battle rifle or self-defense gun. It needs to be reliable and bright.

Many good options nowadays exist for weapon lights, but I always go back to the tried and true ones.

I recommend this full light setup for most rifles, including an HK91/G3.

Identifying your target is crucial; you will need a weapon light if it’s dark.

The Surefire M640U is my go-to for this. It is bright, reliable, and can add a tape switch with a pressure pad for momentary on and off.

These have been around a while and are still trusted as one of the best weapon lights.

Click here to check the current prices of the Surefire M600

They make a Tail Cap Pressure Pad with a button, giving you a constant on and off button. Also, the momentarily one and off button.

With this switch, you can have the most efficient ergonomic light setup and will not have to move your hand to activate it. This will stop you from breaking your shooting grip.

Click here to check the current prices of the Tail Cap Pressure Pad

The tape switch running to a Cloud Defensive LCS Mount works great. I am super happy with this setup and believe it’s the best solution for mounting a weapon light with a pressure pad.

A good weapon light on a rifle is one of my favorite HK91/G3 upgrades and accessories.

Click here to check the current prices of the Cloud Defensive LCS Mount

This light setup is just about the same as what I use on my AR15. Here is my Best AR 15 Upgrades & Accessories post if you want to check it out.

Laser

If you are running this rifle with night vision or plan to in the future, you will need an IR laser.

Sling

The Specter Gear Sling is a good choice for this rifle.

You need a sling to secure your rifle to your body, and if you plan on doing any serious tactical or running and gunning.

I recommend a good two-point sling for a battle rifle. It is the best option, allowing you to transition to a pistol smoothly.

And because this is an HK, you will need an HK-style sling to mount to the Spuhr stock. It comes with a quick adjustment pull tab, an excellent and useful feature.

Remember that you will also need a front sling attachment point on the handguard to use this sling.

Click Here to check the current prices of the Specter Gear Sling

Ammo & Magazines

You will always need more ammo, and with prices at a high, the best idea is to better it whenever you see a sale or buy in bulk.

308 is common and a NATO round, so it’s normally easy to find.

Be sure to click the links and check the current prices and ammo availability because prices constantly change.

• 308 Win / 7.62x51mm Ammo

A positive thing about this rifle is that surplus mags are available and not too expensive.

• Extra Magazines

Enjoy articles like this one? Most people will upgrade their Glock pistols as well, and take a look at my Best Glock Upgrades & Accessories (All Models) to learn more.

Final Considerations

If you want further reading on the H&K G3 History and background, I will link a good article with more information.

Also, if you are a fan of the G3, I will link to an H&K G3 Discussion Board specifically about this platform.

Suppose you do not own a G3-style rifle and are overwhelmed about which clone to purchase. Here is an H&K G3 Buyer’s Guide that will help you decide.

Below is a great video from Ian McCollum over at Forgotten Weapons.

Is the H&K G3 a good rifle?

The G3 rifle is still widely used today, whether it be by professional armies, insurgent forces, or civilian sports shooters. The former two still do primarily due to their abundance and relative affordability, but they’re still regarded as incredibly durable, reliable, and decently accurate.

What is the best G3 clone?

The GI PTR 100 is the most historically accurate G3 clone, featuring no optics rail, an original “SEF” steel lower receiver, and surplus green German furniture.

What military uses the G3 as their standard-issue rifle?

In 1957 German government acquired a production license for this weapon and handed it over to the Heckler & Koch (HK) company. After some local modifications, this weapon was adopted by the German armed forces (Bundeswehr) in 1959 as a standard-issue infantry rifle.

Is the G3 powerful?

The HK G3 rifle has quite a remarkable firing range, making it a very effective war weapon utilizing the 308 cartridges.

What is the civilian equivalent to the G3?

Best G3 Upgrades Questions

If you have any questions, don’t hesitate to drop a comment below. I’ll try my best to answer.

And in case I don’t know the answer, I’ll do some research to find the answer for you.

Furthermore, if you’re curious about the value of any parts not covered in this post, feel free to leave a comment, and I’ll give you my opinion on whether they’re worth investing in.