| | | |  |  | | | | This week’s build of the week comes from one of our employees. It is an AR pistol with interchangeable uppers that allow it to be easily transition from a fireball-throwing .223 to a suppressed .300 BLK.
.223 vs. .300 BLK
The conversation surrounding .223 and .300 BLK has been going on since the Blackout cartridge was introduced. There are benefits to each, and each certainly has its place on an AR pistol build. .223 is one of the most readily available cartridges on the market, it also has a longer range capability as it is a smaller, faster round. This same range capability also means that it has lower energy than .300 BLK closer than 200 yards, and is designed to be suppressed.
The best way to choose between .223 and .300 BLK is, of course, not to. Your standard .223/5.56 AR lower and magazine are also compatible with .300 BLK, so all that’s necessary to swap between the two calibers is a different upper and some different ammunition. For this particular build, we have two complete uppers from Primary Weapon Systems: one in .223 Wylde and one in .300 BLK. Each has its own optic and flashlight, and features a KeyMo mount that works with the Dead Air Sandman-K - a 7.62mm suppressor that works for both .223 and .300 BLK. | | | |  | | | Buying a Complete Upper
Purchasing a complete upper is a great way to simplify the AR building process. Between the gas system, the barrel length, and the handguard there is a lot that needs to fit together right to have a functional and aesthetically pleasing upper receiver, so for newer AR owners purchasing a complete upper is an excellent way to do a partial AR build and get exactly what they want without over complicating the process. This can be especially beneficial if you’re planning to purchase two uppers to switch between .223 and .300 BLK. Purchasing similar upper receivers from the same manufacturer ensures consistency and reliability in your firearm. There are also a lot of ways to continue to personalize an upper even when it’s purchased complete. Between flashlights, red dots, and hand stops there are a lot of aftermarket options to continue to build on a complete upper receiver.
Primary Weapon Systems Mk1 MOD 2 Complete Upper
Primary Weapon Systems is known for their high-quality AR-style builds. Their Mk1 MOD 2 is not only an example of this but probably one of their most iconic pieces. Not only is it a favorite among their employees, but has been used successfully for a wide variety of activities - including hog hunts and SWAT training courses.
The free-float handguard is fully forged and has both Picatinny and M-Lok mounting systems. They’ve eliminated the forward assist to save on weight and equipped the upper with a Radian Raptor Charging handle. There is a 3-setting adjustable gas system and the barrel has a 1:8 twist rate. | | | | | |  | | | Rainier Arms Select Barrel
The Select Barrel is made from a high-precision match blank to Rainier Arms specifications. They are chambered and crowned by hand and feature a 5-groove polygonal rifling that allows for greater accuracy and less erosion over time. The barrels are dimpled, which is a simple thing, but ensures your gas block is properly aligned. They are made in stainless steel - which ensures the longevity of use - and available in both satin or black nitride finishes. What all of this boils down to is that this is a highly accurate barrel designed for hard use and made to last at a price point that makes it accessible to anyone for the purpose of any build. | | | | | | |  | | | Lantac Dragon Muzzle Brake
The Lantac Dragon Muzzle Brake that is featured on this build uses their “Short Energy Pulse system” to reduce the length of recoil so that energy doesn’t lap over shot for shot to throw the shooter off target. The Lantac Dragon features a KEYMO mount, fully licensed from Dead Air, which works with the Sandman silencer line from Dead Air, shown here on the .300 BLK upper. The product is fully licensed from Dead Air and will not affect the warranty on a Dead Air suppressor.
Neomag Sentry Strap
The Neomag Sentry Strap is a nifty addition to this build that might go overlooked by those unfamiliar with the product. It’s a simple strap with a magnetic clasp that wraps around the handguard where it meets the receivers and is used to stage the sling. The idea is that a sling can be kept tucked against the gun when not in use, then a simple tug can deploy it when it is time to sling the gun.
It’s easy to see in Neomag’s video on the Sentry Strap: | | | |  | | | Having options is good, and having multiple available for the same build is even better. The interchangeability between .223 and .300 BLK make that not only possible, but easy. Having two different uppers for one gun is a sensible way to be able to use both of these calibers without building two seperate firearms.
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