Aug M-Lok Handguard With Top Rail

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  • Regular price $119.99

The Underworld Arms Aug M-Lok handguard is 5.5" long and is machined from T6-6061 with a black anodized finish and includes a top rail for extending the iron sight radius. The handguard includes a black oxide 304 SS locking nut, a black oxide 304 SS mounting nut, and a black polymer centering plug for use during install. 

When installed the quick change barrel feature is functional and gas adjustment is accessible, the original grip can be left on or removed. 

The UA Aug M-Lok handguard mounts to the barrel using our proprietary hybrid method that takes inspiration from an AR15 style barrel nut and the Aug's locking flash hider nut. 

To convert this handguard into a quad rail CQC clone see our rail kit availble here

This 5.5" Aug handguard is designed for standard 16" barrels, if you have a 20in barrel you will need to wait for our longer handguard to be released. 

This handguard will fit on A1, A2 and A3 rail receivers, it is not compatible with A3 receivers with a factory scope but we are working on a compatible rail for that model.


To install the handguard remove your muzzle device, degrease your bayonet lug threads and the mounting nuts to remove all oils, apply rocksett or a similar threadlocker to your bayonet lug threads. Thread on the square locking nut with the unthreaded ID facing the receiver, thread on the wing shaped mounting nut with the wing side facing the receiver. Orient the flats of the mounting nut at the 12 o-clock and 6 o-clock and tighten the nuts together. Slide your handguard on and attach it to the mounting nut with the included 8-32 screws. Be sure to use your choice of thread locker on the screws so they do not back out. Test the barrel's quick detach function, if the handguard rail engages the receiver then unthread your mounting nut a half rotation. 

Rocksett has a 24 hour setup time, you do not need to rush the process there is plenty of time to line everything up perfectly. 

Included in the box is a black polymer centering plug that lines up the handguard with the barrel, this does not have to be used during installation but it does make squaring the handguard with the barrel easier and faster. If you chose to use the delrin plug for your installation remember to remove it after you are done. 


Length- 5.5"

Width- 1.7"

Inside Diameter- 1.52"

Weight- 5.8oz

Suppressor and quick mount compatibility:

Any direct thread suppressor 1.5" or less will fit, quick mounts needs to be 1.5" or less to fit. Keymo mounts fit, OSS/Huxworks require the extended flash hider, RC2 are too large. We will update this compatibility list as we receive more feedback from customers. 

Customer Reviews

Based on 9 reviews
John Ellis
M-lok rail

Install was fairly simple especially with some help from YouTube looks amazing still waiting to get to the range to test zero retention of the rail and effect in rifles accuracy but so far seems pretty solid

Camden Thomas
Amazing handguard! Amazing people!

First off, I absolutely love this handguard. It looks amazing and the addition of M-Lok adds a lot of extra mounting surface. Having a light on the front of the gun removes the barrel shadow from when mounted on the side rail entirely.

Once installed properly it feels very solid and makes the already great AUG platform even better.

Second, the folk at Underworld Arms are great people. I recently got a suppressor gas plug and had to remove the handguard for installation of the new plug. While removing the screws that attach the handguard to the bayonet lug mount, I ended up stripping a few beyond use. I reached out to Underworld's customer service and they sent me out replacement screws the next day! You all are great and I really appreciate the support!

Initial impression is good

So far I have no complaints. After a higher round count I’d like to see if it might loosen but other than that, nothing. Good so far

No more shadow issue with flashlight on.

Great modification to my AUG that is practical, high quality and not insanely expensive! Highly recommended!

Matthew K.
Awesome piece for a great price

Rail was easy to install and feels very sturdy. Good price for an AUG rail, shipped quick too . 10/10 would recommend