Mk18/CQBR

When a barrel is shortened, powder that would have burned off inside the barrel now ignites in front of the muzzle. That's the flash we're familiar with. Shorten the barrel and the flash, noise, and concussion all increase, driving a greater need for suppression. This creates a tough paradox: the shooter who shortens their rifle to reduce overall length ends up needing a longer suppressor to handle the larger muzzle blast.

Two strategies emerge for suppressing a short-barreled rifle. The first: I chose an SBR knowing it would be loud because I want a compact gun, so I'll run a short, louder can to keep the total package small. The second: the 10.5" barrel of a Mk18 is so loud that just a few more inches of suppressor can bring it within range of what a full-length gun produces, and the shorter host leaves room for a larger, quieter can. Both arguments have merit. Which you land on comes down to your tolerance for the noise of a small can.

A clone-correct Mk18/CQBR used either a Surefire RC2, a Knights NT4, or nothing, depending on which generation you're cloning. Check out CloneRifles.com to find the details. Both cans are old, heavy, high-backpressure, and absolutely dead sexy. Of the two, the RC2 is more common on the consumer market. It's overbuilt with a stainless steel sleeve and ported baffles that reduce backpressure in a blunt but effective way. My understanding is the RC2 was designed specifically for the Mk18 around 2012, making it the more practical clone-correct choice. The NT4 is gorgeous, though, and when you're cloning, looks matter.

Step outside clone-correct territory and newer tech opens up. The current class leader for the Mk18 is a tiny 4.1" low-backpressure can that tops the Pew Science Mk18 suppressor rankings. The catch is the diameter: 2.1". We suspect that extra girth gives the design enough internal volume to outperform cans twice its length. It's our top pick for this host.

If you want something longer with exceptional backpressure performance that reduces the need to tune the gas system, look at the SilencerCo Velos LBP or the Rhodie 6. The Rhodie 6 also carries some cool aesthetics that echo the dimpling of the clone-correct NT4.

The Knight's NT4 mounts to the mil-spec A2 cage. Easy. The Surefire RC2 uses Surefire's proprietary QD system. Heavy, but solid, with good locking retention and repeatability.

The Mk18 ran a long 4-prong flash hider, the logic being that an unsuppressed SBR needs a larger flash hider to manage the bigger muzzle blast. The risk: 3 and 4-prong flash hiders jet gas directly into the first blast baffle, causing premature erosion. The RC2 addresses this with an oversized first blast baffle built to absorb that punishment.

For most users who plan to run a short barrel full-time, we recommend a muzzle brake instead. It absorbs the initial blast and extends suppressor longevity. Just don't shoot that gun unsuppressed. It will be brutally concussive.

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