Smith & Wesson's M&P 9 Part 2

The AAC Illusion 9 is a good fit with the S&W M&P9 for a number of reasons –

The outer tube and baffling of the AAC Illusion is eccentric to the bore. The feature permits an increase in internal capacity without obstructing a firearm’s sights. The silencer is threaded onto the barrel securely. Then the outer tube is pulled forward and rotated until the larger portion of the eccentric is pointing down and away from the sights. Releasing the tube locks it into position.

Tilting barrel autoloaders often have a problem unlocking or cycling as a result of the added weight of a suppressor hanging off the barrel. The Advanced Armament Illusion 9 utilizes a Nielson type device, their A.S.A.P. (Assured Semi-Auto Performance) system to overcome the problem.

Reading the description, looking at the parts, it all seems a bit complicated. AAC indicates that the silencer is secured to the pistol by a spring loaded piston. On discharge, the silencer floats forward a smidgeon… less than a tad, but more than a skosh, which offloads the weight of the silencer from the barrel. It would seem to me that the resistance created by the spring compression would be a bit like playing “pull my finger” with the barrel, and the snap back from the spring would drive the barrel rearward. But then I didn’t design the dynamic and, of greater importance, the S&W did not fail to unlock or cycle, with or without the silencer in place, and with all ammo utilized.

Reminds me of tiger repellant. A guy had an old stick on his desk. A coworker asked what the stick signified. The guy responded, “It keeps the tigers away”. To which the coworker responded, “Does it work?” To which the guy responded, “See any tigers?” To which my coworkers responded, “Please stop telling that joke”. It was either this or me crediting Nielsen with writing the song “Without You”.

The Advanced Armament Corp Illusion 9 may be configured for wet operation which further reduces noise and port flash. Water, high temp oil or grease, and/or wire pulling gel can be used as an agent to provide up to 30% greater noise reduction. The basic approach to wet operation; with the silencer removed, a 5cc cap full of water is poured  down the rear of the silencer and the silencer is rotated to spread the water evenly over the baffles. The water charge is effective for approximately 50 rounds and will remain for up to three days.  Use of an artificial environment requires more frequent cleaning.

The Advanced Armament Corps Illusion 9 is fairly easy to service, requiring only a spanner wrench that is included with the silencer. The manuals suggests cleaning the A.S.A.P. system every 500 rounds and cleaning the entire unit every 1,000 rounds dray and 500 rounds if used wet.

The tube, inside and out, cleaned up with powder solvent and a bristle brush, then flushed out with mild liquid dish washing detergent and hot water. The baffles cleaned up quickly with a short soak in acetone to avoid cleaners that damage aluminum. O rings are replaced as needed. The manual lists the Illusion 9’s three with McMaster part number references. One nomenclature is incorrectly stated in the manual. listed as having a 14mm O.D., the McMaster part indicated is 12mm. There is no spares kit for this silencer indicated on the AAC website. McMaster sells two of the O Ring in 50 count and one in 25 count, which puts a replacement set at $25 for all with spares to last for some time.

Shooting impressions – factory ammo

Live fire assessment was done with supersonic and subsonic, factory and handloaded ammunition. None were Hollywood movie silent. The bow shock wave of compressed air ahead of a supersonic bullet makes a whip cracking sound even though the actual muzzle blast is significantly suppressed. The subsonic factory and handloaded rounds had no supersonic crack, report was extensively muffled, however, the mechanical sounds of the slide cycling at 20 fps remained as significant noise.

The average dB level of a 9mm round 159. The use of the dry AAC silencer reduces this to 126 dB dry, something similar to a rock concert or thunder clap. Ear protection is still required, however, because the intensity of dB levels progress logarithmically, the benefit to human hearing and perception of loudness is major. Each 20 dB increment increases sound pressure by 10x and perception of loudness by 4x. The conclusion is, not silent in this case, but noise reduction in a very big way. Enough to help protect hearing and improve the shooting environment.

In all cases, velocity increased with the threaded barrel and without the suppressor. Seems about right as the threaded barrel’s rifled bore is 3/4″ longer. With one exception, velocity increased again to a consistently measureable degree with the Illusion 9 silencer in place. My guess is that the minor loss with the Hornady critical duty was the result of increased +P pressure.

With only one factory load performing at subsonic velocity, handloads were assembled to slow things down a bit and to extend the selection of bullets. Remington Golden Saber bullets were chosen because they expand quickly but without shedding bullet weight. Speer Gold Dot 147 grain bullets were loaded, but they have a long skirt and a concave base and tend to bump into the cartridge internal case taper. Subsequently, a short skirted Remington domed “J” bullet was substituted for the last load development. Previous testing showed the J bullet’s expansion and penetration to be on par with the Speer Gold Dot even at low velocity.

There are other bullets that work in a similar fashion, but with a little different geometry. As an example, the Hornady XTP 147 grain JHP bullet and round nose FMJ have a tapered heel.