Mean Arms 9mm bearing delay upper receiver represents a significant step forward in firearms technology.  Building on the lessons learned from existing roller-delayed firearms, Mean Arms developed a new tunable bearing delay system. After getting to put some rounds through this system at this year’s SHOT Show’s Industry Day at the Range I was overly curious how reliable this new system could be. With the help of both Mean Arms and Lake Martin Machine Gun, I put 1,000 rounds through this upper, and here’s what I found.

TFB Review: Mean Arms 9mm Bearing Delay Blowback Upper Receiver

Features

Here’s the product description from Mean Arms on how the bearing delay system works:

The heart of the Bearing Delay Upper Receiver is the unique ball bearing bolt carrier group (BCG). The ball bearings interface with corresponding features in the barrel extension and provide the lockup in battery and the delay after firing. The system can be tuned by replacing the Lifter to change the angle of the surfaces that push the bearings from the inside of the BCG. The bolt face includes our unique center ejector to provide the most consistent ejection of any 9mm AR on the market. The firing pin passes through the ejector.

This bearing delays assembly rides on two rails on either side of the upper receiver. The design is simple and works well as there are fewer friction points inside the receiver.

On the inside of the barrel extension, there are three individual cuts where the bearings index when the upper goes into battery.

This system can be used with any PCC pattern lower or AR-15 pattern lower.  For those wanting to use this system on a pistol magazine lower, the stationary ejector needs to be removed in order to be compatible.  The ejector on the Mean Arms upper also acts as a safety as it doesn’t allow the firing pin to engage until the entire system is in battery.

The upper comes with two lifters that allow the upper to be tuned for different applications like adverse conditions and suppressor use. The lifter is exposed by turning the bolt face 45 degrees and pulling forward.

The lifters are each slightly different in length giving the bearings slightly more or less engagement in order to tune the system.

Usually, the upper ships with two different lifters, but Mean Arms was kind enough to include a third for this test.

Here’s the explanation given to me by Mean Arms regarding the three lifters provided to me for this test:

The typical retail package includes 2 total Lifters for tuning the BCG dwell time.  These components are analogous to the HK Locking piece for their roller delay systems.  The BCG comes from the factory with our ‘K’ Lifter, which should run any of the ammo that you mentioned (124, 147, etc).  The K is a good middle ground.  The typical retail package usually includes one additional Lifter.  However, because you’re writing an article and running multiple different ammo, we provided 3 total Lifters in the package for you to experiment.  The 2 other Lifters we included are the ‘H’ Lifter and the ‘P’ Lifter.  The H Lifter is ideal for low energy ammo (low velocity and/or low bullet weight) where the system could potentially struggle to fully cycle (your subsonic or even a low weight frangible).  The P Lifter is the opposite in that it is designed for hotter high energy ammo.  The P Lifter will slow the cycle time, which like any firearm, is preferable for safety and longevity of mechanical components. However, moving too far in this direction of the chart (see page 44 of the included manual) may cause the firearm to have insufficient energy to cycle reliably.  The P Lifter may reduce perceived recoil.  Information about the Lifters is shown on pages 42-44 of the manual in the box.

Mean includes a 1/2×28 muzzle break with each of their uppers. I wanted to run this upper a little more aggressively and decided to direct thread a Dead Air Mojave 9 to see how the system performed under dirtier suppressed use.

At The Range

I put the Mean Arms upper on an extra rifle length lower I had lying around in order to use the Endomags supplied by Mean Arms for this review.  I was immediately taken back to the first time I shot this system and just how smooth it really is. This time, however, I would be reviewing their 16″ upper (the longest in the lineup) and running the system suppressed. The biggest takeaway was how quiet this setup was at my ear.  A very pleasant surprise when there’s no adverse port noise when swapping back and forth shooting 115gr, 124gr, and 147gr ammo.

The supplied Endomags aren’t something new to the market, but they are a brilliant solution. Running the same pattern magazines as your AR-15 makes for a great training aid, and they’re just as easy to load.

Throughout the test, I kept swapping lifters to see where the sweet spot was for each.  The factory-installed K lifter is honestly the sweet spot when it comes to shooting your regular 115-147 grain ammo.  The P lifter softens the system up to a point that’s almost comical in how low recoil it is, but if you shoot the system weak shoulder or let it get too dirty you can induce a malfunction.  The H lifter is just the opposite and is more aggressive in terms of recoil but runs flawlessly in dirty or adverse conditions.

Each lifter has a slightly different ejection pattern, but each will stack brass in a very neat little pile.  Similar to an MP5 design, the mean upper uses a fluted chamber for functionality and reliability.  Overall, this system is incredibly reliable, and only when I tried to induce malfunctions was I able to.  The rest of the 1,000 rounds ran flawlessly.

Pros and Cons

I tried to find disadvantages in this system, but they’re few and far between. The bearing delay blowback operating design is eloquently simple in incredibly robust.  It allows for a fully free-floating barrel and brings with it reliability and overall ease of use straight out of the box.

There were only two things I didn’t like about the Mean Arms upper, and both are very nit-picky. First was the polymer handguard that does a great job of not absorbing heat, but has a tendency to feel cheap. It’s not a deal breaker, but something I still feel on the fence about after growing fond of aluminum handguards. Secondly, I wasn’t sure why forward assist and forward assist cuts weren’t included in the design.  Not that I ever needed them, but I think they’d be a simple addition that’d add some value

The Verdict

MSRP on the 16″ upper receiver used in this review is $1,500. These can be purchased in five different lengths from 4.5 inches up to 16 inches with MSRPs ranging from $1,400 to $1,575. While I’d be the first to argue the price may be a little high, I was also the first to defend it for the value it provides based on how robust the system is. Any other comparable design will cost you at least $500-$1000 more. To that end, I believe this is the perfect design for shooters already in the PCC market or looking to purchase their first PCC that might already own an AR-15.  Everything from the operating mechanism to the magazines works flawlessly, and it sounds fantastic suppressed.

More information on the Mean Arms bearing delay blowback upper receiver can be found on their product page linked here.  Special thank you to Mean Arms for providing the upper for this review, and to my friends at Lake Martin Machine Gun for supplying the 1,000 rounds of ammunition for this test. Thanks for reading and stay safe.

 

Product Specs

• Caliber 9mm Luger
• Compatible with both mil-spec AR-15 and dedicated pistol-magazine lower receivers
  Works with standard AR-15 buffers
• 5 available barrel lengths: 4.5″, 7.5″, 11″, 14.5″ and 16″
• Includes: Fully tunable ball bearing bolt carrier group
• MA Upper Receiver – slick side billet machined aluminum upper receiver
• MA Handguard – free float hybrid metal/polymer design
• MA Charging Handle – new ambidextrous design
• MA Muzzle Device – exclusive machined design reduces recoil and muzzle flash
• Also included with the purchase of the Bearing Delay Upper Receiver:
• 1 additional Lifter for tuning the system (2 total included)
• 2 Ejectorless EndoMags (PMags NOT included)
• This product carries a MEAN Lifetime Warranty! If you have an issue please contact our support department via email at support@meanarms.com. We are here to help!