Growing up competing in various forms of motorsports, I appreciate the fine details and skill needed to build a fast, lightweight and capable machine. Exotic materials like carbon fiber and titanium alloy as well as engineers willing to push the limits of lightweight designs in order to deliver a winning edge for their driver on race day. All of these qualities can be found in Boise, Idaho at 2A-Armaments headquarters. 2A-Armament products range from titanium takedown pins to complete AR’s and everything in-between. I recently received a Regulated Bolt Carrier (RBC) from 2A-Armament to try to solve a minor problem I was having with my Daniel Defense Mk-18 when used with the Surefire SOCOM Suppressor.

Regulated Bolt Carrier
2A-Armament RBC vs. Daniel Defense BCG

Much like the engine is the heart of a race car, the bolt carrier group is the heart of the AR-15 rifle. It’s ability to cycle over and over reliably in a hostile environment is a true testament to it’s original design. Is there room for improvement? Of course there is. For the same reason the Ferrari F1 team doesn’t use a factory engine in their race cars, we shouldn’t settle for the overweight bolt carrier group in our AR’s. The crafty engineers at 2A-Armament have whittled away any unnecessary material in their Regulated Bolt Carrier to achieve a sleek, lightweight engine for your AR-15. Plus, they’ve added a titanium regulating gas-gate under the carrier key. This gate allows easy adjustability of the gas system in your AR-15. If you use a suppressor like I do, this alleviates the need for an adjustable gas block to tune the system to work reliably suppressed as well as un-suppressed. The adjustable gas-gate in the 2A-Armament Regulated Bolt Carrier can be accessed through the ejection port of the rifle with a T-6 Torx driver. This allows the user to adjust the valve while still installed in the rifle making tuning a snap.

Regulated Bolt Carrier
2A-Armament RBC vs. Daniel Defense BCG

The stock Mil-Spec bolt carrier group supplied with the Daniel Defence Mk-18 and most other AR rifles weighs in at 11.6 +/- ounces. By removing unnecessary steel from the bolt carrier group and fusing a 7075-T6 aluminum back half, 2A-Armament was able to reduce the reciprocating mass by 32% delivering a RBC of only 7.9 ounces. Any reduction in mass of a reciprocating part pays huge dividends in both performance and longevity. Additionally, the RBC’s components are all heat treated, the bolt is further cryogenically treated and everything is QPQ Nitride coated to reduce wear.

Regulated Bolt Carrier
2A-Armament RBC vs. Daniel Defense BCG

In the video below, (sorry for the wind noise) you’ll see just how easy it is to tune the gas system using the 2A-Armament Regulated Bolt Carrier. My Mk-18 was slamming the stock BCG due to the “over gassed” condition created by the suppressor. To adjust that, I found a setting within the Regulated Bolt Carrier that both cycled the rifle reliably with the appropriate amount of gas and held the bolt open once the magazine was empty. A good measure of the proper amount of gas regulation is achieving a perpendicular ejection of the spent cartridge. When I first purchased the Daniel Defence Mk-18, I had to swap the buffer to get it to cycle reliably with the suppressor installed. Rather than swap buffers and/or springs when alternating between firing suppressed and un-suppressed, now I simply adjust the regulating gas-gate. 2A-Armament does not supply the needed T-6 Torx driver with the Regulated Bolt Carrier but they are available anywhere they sell tools for less than $5.