Recently police special reaction teams and hostage rescue units have begun to transition away from pistol-caliber s, like the 9mm HK MP5, to carbines like the Colt M4 and CAR15. The theory behind the old reliance on pistol ammunition for tactical applications was that subsonic or transonic soft-nose handgun bullets would not penetrate through soft cover nearly as far as high velocity full metal jacket rifle ammunition. Thanks to an in-depth study by the Dept. of Justice, however, we have learned the fallacy of such this logical, but flawed presumption. It turns out that the hollow cavity in pistol bullets would fill with material like sheetrock and act like solids, penetrating through walls into neighboring rooms. Meanwhile, it was discovered that the high impact velocity of .223 ammunition caused the bullets to deform or fragment against sheetrock, greatly reducing their penetration. There was one hidden benefit to the use of pistol calibers in subguns, something we didn't fully appreciate until we switched to .223 carbines - the noise level. Pistol ammunition, with considerably less propellant than rifle ammunition, gives far less muzzle blast than a .223. One round of .223 in a confined hallway or narrow stairwell produces a painful, ear-shattering noise level. By contrast, a 9mm is disturbing but not disastrous, allowing officers to make entries into inner city projects, trailer homes and other enclosed environments. The chance of irreparable hearing damage is significantly increased with the rifle-caliber carbines, we discovered. During emergency situations where an officer becomes stressed, auditory exclusion occurs which diminishes the effect of the pistol cartridges being fired in close proximity. But remember, hearing loss is cumulative and will occur from repeated exposure to pistol and fire.

Hearing Loss
Recently, several shootings in my jurisdiction in southern California have caused officers to damage their hearing to what a clinical diagnosis would call a severe hearing loss. The damage was attributed directly to the fact that they were using .223 short-barreled carbines in enclosed environments. One SWAT officer, while conducting training inside a bus using live fire, lost his foam hearing protection and another officer fired two shots in close proximity to his brother officer, causing the total loss of hearing in one ear for 48 hours. After two days he was very fortunate to resume his hearing at what appeared to be a normal level without any permanent disability. In another situation, two officers went into a super- market in Irvine, Calif. to confront a mentally deranged suspect running amok with a samurai sword. The maniac eventually killed two people inside the market, prompting an active shooter response in which the officers deployed short-barreled M4 rifles and went after him. One of the officers received serious hearing loss as the result of rounds fired to stop the perpetrator. As of this writing, it is uncertain if the cop's hearing will ever come.

The Suppressor Alternative
For the past several years, I have carried a Heckler & Koch MP5 SD suppressed 9mm submachine -gun as my permanently issued SWAT weapon. I carry the MP5SD securely locked in the trunk of my squad car while working patrol. One evening we got a call of a "man with a knife" at a busy intersection. I responded and, realizing that the number of innocent bystanders would prohibit the use of my shotgun, I grabbed the MP5SD from the trunk. I ended up using that suppressed weapon yet I received no hearing loss whatsoever, partially because of the pistol caliber, but mainly because the weapon was suppressed. During training with my suppressed MP5, I don't have to wear ear protection. I find that I was much more effective while hearing everything happening around me, and that the firing of my weapon did not cause my SWAT teammates to lose focus on their jobs when I fired the 9mm. Now it's true that there are passive electronic hearing muffs that allow officers to retain their normal hearing in a tactical environment, yet remain protected from gunfire noise. However, these muffs are bulky and can easily become dislodged during dynamic situations. Moreover, hearing muffs are incompatible with gas masks and, due to the fluid and fast-moving situations that we often encounter, there isn't always time to put on your "ears If that's not enough, obtaining a good cheek weld with muffs can be awkward. If the "ears" interfere with the proper positioning of the shoulder stock, it can affect the accuracy of the shooter.

By placing a suppressor on the weapon, it reduces the noise to a safe level and officer can now deploy the weapon in any situation without worrying about hearing loss. During tactical situations, suppression of the noise allows cohesive unit operations and supervisors to be able to control the incident because they are not being overwhelmed by the loud noise and concussion. Suppressors only extend the length of the barrel approximately 3" to 4" and with advanced designs like the new SureFire M4FA, the bullet's velocity is actually increased, improving the terminal ballistics and, ironically, lessening the chance of over-penetration. As I transition to a .223 for special situations, I now have a suppressor for my M4 that allows me to be able to operate without endangering the hearing of myself or a teammate. For budget-minded departments, the cost of a suppressor is relatively low compared to the cost of paying an officer's medical claim for hearing loss, never mind the cost of a lawsuit from a citizen. The bottom line is that a suppressor allows an officer to better protect and defend the public, which is why we pinned on a badge in the first place.

Bill Murphy is a 24-year-veteran Senior Police Officer assigned to Patrol and SWAT, with a major California municipality. He is a Use of Force Instructor, Gunsite Range Master, certified Surefire Institute Instructor and he owns and operates Firearms Training Associates, a southern California training center for weapons and tactics. The website address is www.FTATV.com