Anonymous
Anonymous asked in SportsOutdoor RecreationHunting · 1 decade ago

How come .45 weapons with silencers are quieter than 9mm?

Like i was watching TV and when they were comparing suppressed weapons and one guy shot a Glock17 supressed and it was a little loud. And then the other guy shot a USP.45 and it was much quieter and a more soft sound. Anyways whats the reasoning behind this?

10 Answers

Relevance
  • Keoni
    Lv 7
    1 decade ago
    Best Answer

    "The reasoning behind this" is as follows:

    The speed of sound is approximately 1140 feet per second. Bullets that travel near the speed of sound are considered transonic, which means that the airflow over the surface of the bullet, which at points travels faster than the bullet itself, can break the speed of sound. In weapons firing supersonic bullets(faster than the speed of sound), the supersonic bullet itself produces a loud and very sharp sound as it leaves the muzzle in excess of the speed of sound and gradually reducing speed as it travels downrange. This is a small sonic boom, and is referred to in the firearm field as "ballistic crack".

    The .45 ACP is an excellent choice, since the standard 230 grain loading is both powerful and subsonic. Most of the 9mm loadings have a higher velocity than the approximate speed of sound. The exception is the subsonic 147 grain loading that typically have velocities from 900 to 980 feet per second.

    The type of firearm to be suppressed also affects suppressor efficiency. Guns with the least gas leakage are best, so a sealed breech (e.g. bolt action or lever action) is preferable and can be suppressed to the point that the click as the striker or hammer falls is the loudest sound of firing. Most semi- and fully-automatic firearms still produce a significant amount of noise from the gun cycling and the leak of high-velocity gas from the breech. Revolvers, due to the gap between the cylinder and barrel, cannot be made quiet.

    Here is a very good explanation of silencers:

    http://en.wikipedia.org/wiki/Suppressor

    This link explains the logistics of a sonic boom:

    http://en.wikipedia.org/wiki/Sonic_boom

    Source(s): NRA Life Member Certified Handgun Instructor
  • Anonymous
    1 decade ago

    It's TV, it's for entertainment, not information gathering. This includes stations like the Discovery Channel.

    a 45 ACP generates more gas that you have to slow down to low velocity than a 9mm does. Using the same size supressor, the 45 acp will be less supressed. Or put another way, the 45 acp requires a larger supressor.

    Now, assuming you can fully brake all the hot gasses, then the 45 acp's slow speed helps it out in the noise department. It doesn't break the sound barrier so you don't have the sonic whistle that the 9mm is going to have.

    and finally, machine quality plays a part. A high quality supressor is going to do better than a cheap one, or a hand-made one.

  • 2A
    Lv 7
    1 decade ago

    Its the crack of the 9mm faster ammo and the 9mm being super sonic and most .45 ammo that I have seen is sub-sonic at sea level.Speed of sound at sea level = ~1116.13 feet per second but at 11000+ feet, it's 660 mph or 968fps. Now before the arm chair elitist come screaming I know SOME .45 rounds go past 1116fps but, not the average 230gr.

    Source(s): z
  • Anonymous
    1 decade ago

    A 9mm is faster than a 45acp round therefor they make more sound because they tend to break the soundberier creating a sonic boom unless they use subsonic ammo. The 45 is slower than the speed of sound so it cannot create a sonic boom.

  • How do you think about the answers? You can sign in to vote the answer.
  • Anonymous
    1 decade ago

    A suppressor doesn't really help much if you're still using Super-sonic ammo. So a lot of your 45 ACP ammo is more sub-sonic...big and slow while 9mm is small and fast.

  • Anonymous
    1 decade ago

    maybe it's the gun's action that's making the noise, some do make quite a bit of noise but it's usually overpowered by the cartridge and bullet.

  • 1 decade ago

    .45's tend to have a slower bullet velocity due to twice the standard weight of a 9mm, which means less air is hitting the bullet in a certain time, causing less noise (less than supersonic)

    (but .45's have more stopping power)

  • Anonymous
    1 decade ago

    yes i see a lot of this the gun fx guys or gals miss a lot of things um my fav is sneaking up on a person and racking the slide ,, the open bolt,, multi fire no reload and the most is a full auto missing everone in the room,,,,,,,,,,,,, agree with the submunitions theory ,

  • 1 decade ago

    subsonic

  • 1 decade ago

    cause they have silencers on.

Still have questions? Get your answers by asking now.