Operating gunsmiths interested in maintaining profitable shops are wise to keep an eye on emerging trends. Conversations with several gunsmiths recently revealed that some of the most profitable, ongoing work for them includes AR-15 builds (no surprise there), 9mm carbines of various makes (influenced from Pistol Caliber Carbine competition), and suppressors. All three of these are nicely put together in this offering from Desert Design & Development.

D3LLC is a design and manufacturing company making integrally-suppressed weapon systems for civilian and law enforcement markets. The company’s founders have over 30 years of combined firearm design, manufacturing, and sales experience.

The DEFCON 4SD from D3LLC is an integrally-suppressed barrel system based on the Heckler & Koch MP5-SD designed for 9mm carbines and pistols based on the AR-15 platform. Using a 6.75” match-grade barrel and ports that are designed to support the host suppressor, the 12” suppressor features a large expansion chamber and unique barrel support and baffle system. Combined, it’s 13.75” from chamber to muzzle.

Colt released the first 9mm AR platform, which is the closest thing to a “standard” for this. Similarly, the DEFCON 4SD is as close as a standardized “drop-in” option for 9mm AR-15s.

“We have created a 9mm AR barrel that resembles the MP5-SD barrel and made it more efficient and accurate,” said James Seto for D3LLC. “The mated high volume suppressor works in tune with the ported barrel and produces amazing suppression quality, even for a blowback carbine. The ports allow some of the gasses from the 9mm projectile to be bled off into the expansion chamber and reduce the muzzle velocity down to subsonic levels. Off the shelf ammunition from 115gr to 158gr produces a sound level from around 123dB to 110dB, respectively. Our DEFCON 4SD is a proven system and is the same suppressor system we use on our 9SD Complete Integral 9mm AR Upper Assemblies, as well as our D3-9SD, The Ultimate Urban Carbine.”

For further information, contact D3LLC Sales & Operations (623/256-1827,

Read more in the April 2018 issue.

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