![]() ![]() The SK Subsonic Hollow Point brought plenty of squirrels out of the trees last year for me. That leads me to the round I had my CZ 452 American Suppressed rifle doped for last year. Just don’t be disappointed when your sales clerk tells you the subsonic loads are “quiet” and you have to wear your hearing protection at the range because they still bust your ears.After testing the Eley Subsonic HP ammo and finding the results I did, it is only natural for me to continue to test my other preferred squirrel rounds. So the subsonic is useless unless used in a silencer? No, it will be quieter because of the subtraction of the sonic “crack” the load will not have. Most silencers are still OSHA approved to be used without hearing protection no matter what load you shoot in it so they are still much quieter even with high velocity loads. I usually demonstrate the difference in decibels to them from high velocity to subsonic loads and they are then convinced the silencer works as advertised. Many of my silencer customers complain to me that their silencer “just don’t work!” My first question to them is, “Are you shooting high velocity loads in the host weapon?” 100% of the time, their answer is yes, they are just shooting what they have always shot in the firearm. 9mm in target loads 147 grain or greater, 45 acp target loads in 230 grain or greater among others) and a 22LR is really close to subsonic anyway, you even specify “high velocity” if you don’t want subsonic in it. In many calibers, the loads are “naturally” subsonic (i.e. This is not to say a subsonic load isn’t powerful, it is. A high velocity load is often preferred for hunting while a subsonic load is mostly used for sport shooting. What do we give up in our subsonic loads? Well, the slower round will of course do far less damage than a high velocity load. Thusly, a valuable load for the silencer shooter, a subsonic load is a “must have” if the entire shot needs to be quiet. A high velocity load will be quiet at the host weapon through a silencer but will eventually “crack”. So what does this matter? Well, a subsonic load shot through a suppressor (silencer) will stay quiet because it will not produce the “crack” in flight. A subsonic load stays slow enough that it will not break the sound barrier. A high velocity load will break the “sound barrier” and have a supersonic “crack” as the bullet breaks this barrier somewhere in it’s trajectory. Where the difference comes in is at the max velocity “crack” of the bullet traveling through the air. I stated earlier that subsonic loads were still loud at the host weapon and this is true. So why make subsonic loads if they’re loud too? Good question. If you really need to figure the subsonic coefficient of a load, this is where to start your studies. I have no idea what it means though so, if you’re still interested, there are online calculators to help you figure the same thing except much easier! A couple are located at and . For general equations of state if classic dynamics is used, the speed of sound c is given by The above calculation chart is available at Wikipedia. Thus the speed of sound increases with the stiffness (the resistance of an elastic body to deformation by an applied force) of the material, and decreases with the density. In general, the speed of sound c is given by the Newton-Laplace equation: P is a coefficient of stiffness, the bulk modules (or the modulus of bulk elasticity for gases), ρ is the density Staying below this number will yield you a subsonic figure. ![]() If you’re pretty smart with math, you can use the equation below to figure your actual speed of sound. This changes with many factors including temperature, altitude etc. To be rated as subsonic, the load needs to be at or below around 1125 feet per second. The major difference in these loads is the top speed the bullet will eventually reach. For all intensive purposes, subsonic loads are just as load at the host weapon as higher velocity loads. I hear many “ammo salesmen” explain that subsonic loads are “much” quieter than factory loads. First of all, the word subsonic actually means “below the speed of sound”, this is a much overused and misunderstood term. How do we tame that crack though? Well, many folks believe it’s with the use of subsonic loads but this isn’t completely the case, however. Ah, the hush of a otherwise deafening boom found in most handguns is a beautiful thing. ![]()
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