Into the Rabbit Hole
A close look at the Maxim Defense Industries MD-415 AR upper
s ometimes you’ll lock onto something that piques your interest, whether it's a firearm platform or even a single accessory, and it’ll start you down the path of discovering other new things that you haven’t encountered before. Thanks to the internet, new discoveries are found quite often nowadays. We jumped into a rabbit hole a couple of years ago when we discovered the world of personal defense weapon (PDW) stocks and a company called Maxim Defense Industries.
When Pdw-style stocks hit the market and became a popular trend a few years back, one stock rose to the top and became a
favorite of PDW builders, especially among short-barreled rifle owners, far and wide.
You could say that the Maxim Defense Industries CQB stock became the poster child for the Pdw-style stock movement. It is pricey, but its solid feel, advanced design and fine craftsmanship are beyond reproach. Maxim is back at it, only this time they’re onto something completely new to them.
The designers and engineers at Maxim are constantly looking for different, better ways to do things. Not looking to frivolously design things for design’s sake, they understand that form follows function and function is of the utmost importance. Lucky for us they also know that attention to form makes for a better-looking firearm, and there’s nothing wrong with that in our book.
This time around, Maxim’s attention shifts from the rear of the gun to the top of it. We were offered the opportunity to get an advanced look at Maxim’s completely new MD-415 R-DI 11-inch complete upper. The “MK-18” style upper receiver is made for AR-15 platform rifles and is the first complete upper release for the company.
The upper receiver assembly features plenty of exclusives such as Maxim’s MD 7075 billet upper receiver and MD Slimline handguard. Both pieces feature precise machine work and true to Maxim’s previous offerings are endowed with visually pleasing forms.
The upper receiver features clean lines and is topped with a lightened Picatinny rail. A relief runs the entire length of the receiver and into a matching relief on the rail of the handguard, helping with weight reduction and adding a modern look to it too. The unique look of the handguard really got our attention. It locks onto the receiver with a single screw and is quite slim, measuring only 1-5/8 inches in width. The handguard has a full-length top Picatinny rail and is lined with M-LOK attachment points on the rest of its surfaces. It’s not all about looks, however.
The heart of the upper is an 11-inch cold hammer forged barrel made by FN Herstal
“The upper receiver assembly features plenty of exclusives such as Maxim’s MD 7075 billet upper receiver and MD Slimline handguard.”
and is chambered in 5.56 x 45mm NATO. Yes, the same FN that brought you favorites like the SCAR 17S and M249 SAW. The barrel that sits inside the MD-415 is actually machinegun-grade and chromelined for ease of cleaning and longevity of life. Its 1/9 twist rate can stabilize a variety of bullets in both 5.56mm and .223 Remington calibers. As good as that sounds, we haven’t even gotten to the best part yet. If the barrel is the heart of the MD-415, it’s Maxim’s innovative gas-regulating, direct-impingement system that is its soul. Yes, we said gas-regulating. Unlike most other AR-15S, where the amount of gas return you get is limited by the barrel’s gas port size, or if you’re lucky, by an add-on adjustable gas block, the MD-415 features a built-in system called the Maxim Regulated Direct Impingement Gas System. Maxim’s shorthand for this system is R-DI.
The R-DI allows the shooter to fine-tune the weapon’s gas system with the simple pull and twist of a self-locking knob found at the gas block of the upper. It features four gas adjustments, which include (in order of least amount of gas return to most) Off, Suppressed, Standard and Adverse. Piston-driv-
“The designers and engineers at Maxim are constantly looking for different, better ways to do things.”
en AR-15S have a similar setup, but it’s rare to be found in DI guns.
We found the adjustments easily made with positive clicks felt and heard between each of the adjustments. No tools required—the knob can be turned by hand, although we recommend avoid feeling the burn by using gloves if making adjustments after the gun has been fired. A bullet-sized hole is provided if you wish to use a tool as well.
The upper also incorporates a slick nickel boron-coated enhanced bolt carrier group for reliable functioning. The barrel is topped off with the old standard, an A2 flash hider. Some readers would be interested to hear that we’ve heard that this upper has been selected and might already be in use by an agency for official government business. Maxim says that the commercial version will be kept pretty much identical to the dot-gov version as possible.
How much will this fine piece of machinery run you? We wondered the same thing. Unfortunately, at the time of this article’s printing, the MSRP was still not determined. We were fortunate enough to be some of the first to get a test piece and wanted to show it to you as soon as we could. Check Maxim’s website to see if a price has since been released.
During our time with the upper, it performed flawlessly and oozed innovation and style that you come to expect from Maxim Defense. We added a Surefire flash hider to the upper so we could test its suppressed functionality. With a Surefire SOCOM762-RC2 suppressor attached, it also shot without so much as a hiccup.
The adjustability helped us run a variety of ammunition and kept us from eating too much spent gas.
Being able to regulate gas right out of the box in a DI gun is great if you’re fortunate enough to run suppressed. It also works well if you need to fine-tune your gun for differently powered ammunition as well. The look and feel of this upper receiver is everything we would expect from the innovative company. If you’re already a fan of Maxim’s PDW stocks, you’ll definitely want to take a good close look at the MD-415 R-ID upper. If Maxim Defense Industries is new to you, welcome to the rabbit
hole. Your journey is just beginning.
“regulating gas is great for suppressed, or for differently powered ammunition.”
Maxim Defense’s MD-415 R-DI upper assembly is made for AR-15 platform rifles and is the first complete upper release for the company.
A relief runs the entire length of the receiver and into a matching relief on the rail of the handguard to help with weight reduction. The handguard locks onto the receiver with a single screw, with a full-length top Picatinny rail and M-LOK attachment points across its other surfaces.
The upper receiver incorporates a slick nickel boron-coated enhanced bolt carrier group for reliable functioning. According to Maxim, the commercial version of the MD415 will be kept as close to the dot-gov version as possible.
The R-DI allows for tuning of the weapon’s gas system with the simple pull and twist of a self-locking knob found at the gas block of the upper. It features four gas adjustments: Off, Suppressed, Standard and Adverse.