[Big 3 East] Closer Look At The Maxim Defense PDX – SCW Brace

Nicholas C
by Nicholas C

Last year Maxim Defense attended Big 3 East with a selection of HK416s and MDXs. SHOT Show 2019 was extremely frenzied with their unveiling of their 5.5″ PDX. Well, Maxim Defense showed up at this year’s Big 3 East and we got to get a closer look at the PDX along with their new SCW Brace for the PDX line.


The SCW Brace is similar to their CQB brace, however, it is a new design as the bars are narrower.

The SCW uses a proprietary bolt and buffer system. You can see how the bolt and buffer interact below:

These are the Maxim MPX/MCX collapsing braces and stocks.


Last year at Big 3 East, we saw the prototype for the M-Rax MLOK rails. Eric posted about them last October. The M-RAX rails are a little different than your run of the mill MLOK rails. On a typical MLOK rail, you have a T-Nut and a bolt. There is a slight problem with this design and that is due to the fact that the bolt can encroach into the space occupied by a muzzle device or suppressor.

The M-RAX design flips this on its head. It uses a T-bolt and a nut. So the bolt does not touch anything inside the handguard.

You can see the T-Bolt and how close it sits next to the muzzle device.

With the muzzle device removed, you can see the T-bolt of the M-RAX rail. There are no exposed bolts.

So instead of encroaching into the handguard, the end of the bolt pokes through the nut.

One downside to this design is that the thickness of the rail is mandatory.

Here is the M-RAX alongside a typical polymer MLOK rail.

You can see the bolt poke through the T-nut on the right-hand side. But the M-RAX is taller.

PDX Hate Brake

If you recall, at SHOT Show, I discovered that the PDX Hate Brake creates a square muzzle flash.

This is due to the 3/8″ drive socket shaped hole in the Hate Brake.

The Hate Brake is similar in design as a Bulgarian Krink brake. It consists of a cone and a cylinder.

There are two versions of the Hate Brake, round or octagon. The octagonal design is the fit under handguards.

The Hate Brake was designed as a booster for extremely short SBRs to help cycle the gun. It also works very well as a linear comp redirecting a majority of noise forward away from the shooter and people alongside the shooter. At Big 3 East, Arsenal was right next to Maxim on the shooting line. They had a full auto short barreled Krink with a Krink cylindrical brake. It just so happened that Maxim had their 7.62×39 PDX on their far right. So while I was filming my friend shoot the 7.62×39 PDX, I could hear and feel the Arsenal gunfire. It was downright obnoxious with concussive muzzle blast. It was fine for the shooter but not if you were on either side of the gun. In stark contrast, the PDX only has a 5.5″ barrel compared to the 8″ barrel on the Arsenal gun. Even with the shorter barrel, the Hate Brake works. I was not bothered at all by the PDX firing right next to me and it was even closer to me than the Arsenal gun.

With 55gr 5.56 Maxim was getting an average of 1,929fps. 124gr 7.62×39 yielded 1,772 fps out of the 5.5″ PDX.

They are currently collaborating with Fort Scott ammunition. Fort Scott has a round that tumbles upon impact and they will be making ammo tuned specifically for the PDX.

Maxim is working on .300BLK PDX that can fire supersonic as well as subsonic ammo without needing to change any settings. In 2020 they will come out with a 9mm PDX.

The PDX also features a replaceable gas jet. Shooting 5.56 or 7.62×39 out of a 5.5″ barrel will cause excessive wear on the gas block so Maxim designed the gas block to be user serviceable.

On an interesting note, the PDX complete firearms will come packaged in laser-cut foam. DO NOT THROW IT AWAY. Take the foam out and put it into a 1525 or 1535 Pelican Air Case. They have similar interior dimensions. The 1535 is just deeper.

The PDX can be suppressed, however, there is a caveat. Maxim does not approve the use of suppressors on the PDX unless it is their suppressors. They had prototypes at SHOT Show. Due to the extreme pressures of such a short barrel suppressing the PDX with a third party suppressor is “use at your own risk”.

The PDX will be shipping out later this month. They will come equipped with the Reptilia CQC grip.

They will be offered as factory SBRs or Pistols with SCW braces for around $2,000. You can get the upper kit which comes with everything but the lower receiver but you do get the CQC grip for $1,799. The upper receiver alone will be sold for $1,299.

Nicholas C
Nicholas C

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  • MediumSizeTex MediumSizeTex on Apr 11, 2019

    Problem: There are four competing designs for attaching accessories to firearms

    Solution: We should make a universal accessory attachment system!

    Problem: There are five competing designs for attaching accessories to firearms

    • See 4 previous
    • James Wilson James Wilson on Apr 12, 2019

      @HLS30 Q's system...