As the popularity of sounds suppressors for hearing protection continues to grow, more companies are offering their own proprietary units for sale. A relatively new company on the scene is Dead Air Armament. The company was launched by Mike Pappas (a founder of SilencerCo) and Todd Magee (former SilencerCo designer) to provide high quality suppressors for military and law enforcement as well as civilian applications. Their first series of suppressors to arrive on the market were the .30-caliber Sandman suppressors for high-power center-fire rifles.
For 2015, the Dead Air line up was expanded to include the Mask line of rimfire suppressors. Recently, I had the opportunity to spend a day at the range with Mike and Todd to learn more about the Mask HD, or Heavy Duty, version of this new suppressor.
Building sound suppressors is a tricky technical balancing act of blending features, materials and external dimensions to get a just-right product to satisfy the needs of the customer. Some companies opt to use lower grade materials and processes in order to keep the cost down. But Dead Air has opted to go the high-end suppressor route, using top quality materials and features that cost more to produce but make for a better suppressor.
The Mask HD suppressor, or silencer if you prefer, is 5.1" long with a 1.07" diameter and a weight of 6.8-oz. It's slightly heavier because it uses 17-4 PH stainless steel baffles and end caps instead of aluminum, while the exterior tube is constructed of light weight Grade 9 Titanium to help keep the weight down. The tube is treated with a durable matte black Cerakote finish while the end caps are treated with a tough black nitride to handle tool interactions without marring the finish. 
The baffles are a highly optimized version of the K-baffle called a "compressed-K" configuration. This design allows for excellent sound reduction in a compact package. Many rimfire suppressors suffer from a loud first-round pop, or FRP. FRP occurs when oxygen in the suppressor is mixed with un-burned powder, causing the report to be louder. After the first shot, this phenomenon goes away, resulting in subsequent shots with a softer report. The FRP of the Mask is so low that the first shot is often indistinguishable from subsequent shots.
The two locations inside of a sound suppressor where the movement of gases are most likely to affect bullet placement are where the bullet enters the suppressor (the blast baffle located next to the muzzle) and where the bullet exits and transitions into the outside atmosphere (end baffle). These two critical baffles are symmetrical with no cross-jet features to ensure optimal accuracy.
The baffle stack is fully encapsulated and sealed, including the area surrounding the blast chamber. This keeps most of the carbon and lead deposited by dirty rimfire rounds inside the baffles allowing them to be more easily removed for cleaning. Nevertheless, some residue will leak out into the tight space between the baffles and the exterior tube. That's why these baffles are designed with minimal contact points so they will break free when pushed out instead of becoming welded to the tube by fouling.
The Mask's back cap and front cap are tightened or loosened with the use of special adjustable wrenches. The tools allow the suppressor to be snugged down tight enough to go under the hand guard or barrel shroud of a rifle without the tube twisting free from the back cap and leaving it behind when the suppressor is removed from the host rifle. In short, the Mask HD provides superior sound reduction and minimal FRP in a small package that is durable and easy to clean.
One of the advantages of the Mask HD over dedicated .22 LR suppressors is its rating for rimfire rounds ranging from the .17 HMR all the way up to the hot .22 Mag. It will also work with FN's 5.7x28 mm center-fire round. But for testing at the shooting range, we stuck to .22 LR for the purposes of checking sound levels. The two test guns used with the Mask HD included a 4.4" barrel Walther PPQ 22 pistol and a Smith & Wesson M&P 15-22 MOE with a 16.1" barrel. Both guns arrive from the factory with suppressor-ready threaded muzzles. 
Although .22 rimfires seem quieter than larger calibers, don't be fooled into thinking that they are safe to fire without hearing protection. Generally speaking, unsuppressed gunfire typically produces noise levels between 140-190 dB (Decibels) depending on the firearm and ammunition used. Extended exposure to noises that reach a decibel level of 85 or higher can cause permanent hearing loss. Without a sound suppressor installed, the Walther pistol produced a report that averaged 155 dB while the M&P 15-22 averaged 140 dB. 
As the louder of the two guns on hand, the Walther was checked for noise levels with the Mask HD installed using two sub sonic rounds (CCI Standard Velocity and Federal American Eagle Suppressor), and a faster high velocity round (CCI Mini Mag). The suppressor was fired 10 times (FRP + 9 more shots) near a microphone and recorded for each load tested. Those shots were then averaged together for a final number. As expected, the CCI Mini Mag turned in the highest dB rating of 118.7 but that's fairly quiet for this load when compared to other suppressors. The two sub sonic loads were neck-to-neck for the quietest load with the CCI Standard Velocity averaging 114.4 dB and the American Eagle Suppressor averaging 114 dB. Firing the CCI Standard Velocity loads in the Smith & Wesson M&P 15-22 with the suppressor in place produced an average sound level of 115.6 dB.
The Dead Air Armament Mask HD sound suppressor was a real pleasure to work with. It's exceptionally well made with a high level of attention to detail and quality craftsmanship. This suppressor is backed by the company's no questions asked lifetime warranty and will provide years of enjoyable sound reduction.
Specifications
Manufacturer: Dead Air Armament
Distributor: BPI Outdoors
Model: Mask HD
Caliber Rating: .17 - .22 Rimfire, 5.7x28 mm
Diameter: 1.07"
Length: 5.1"
Weight: 6.8 oz
Tube: Grade 9 Titanium, Matte Black Cerakote
Baffles: 17-4 PH Stainless Steel, Natural Finish
End Caps: 17-4 PH Stainless Steel, Black Nitride
Thread Size: 1/2" x 28n TPI
MSRP: $449
