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Odd firearm question

  1. Nov 19, 2012 #1
    Ok it's been way too long since I've done this type of math and I ran across this forum, I how you all can help, here's what happened:

    I went out to the woods to do some shooting. For one of the guns it was the first time I shot it with a silencer. Apparently it wasn't mounted right and the damn thing shot right off the end I assume because of a baffle strike. Unfortunately it was in an area with a lot of brush and a ton of leaves. I looked a bit before it got dark and couldn't find it but obviously I really need to and yes I am legally possessing it :)

    So what I'm looking for is the theoretical maximum distance that it could have traveled so I can determine how much of a search area I need to cover. Here's some data:

    Bullet Weight: 55gr
    Approx muzzle velocity: 3000fps
    Weight of silencer: 18.8oz
    Height above ground: about 5.5 feet
    I was shooting at a downward angle but I don't remember how much down so maybe assume zero?
    There would have been some friction between the mount and the suppressor but no idea how much.

    Thanks for your help
  2. jcsd
  3. Nov 19, 2012 #2


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    Staff: Mentor

    Welcome to PF!

    What an excellent opportunity to learn about conservation of momentum!


    M1 is the mass of the silencer.
    M2 is the mass of the bullet.
    M3 is the combined mass.


    Once you've found the max velocity, distance is going to be tougher though.
  4. Nov 20, 2012 #3
    Done this twice with a suppressed .45 (in WA state -- yes it is legal there!).. in my experience the suppressor went about 5 ft, both times. No damage.

    russ_watters already gave you the simple [worst case scenario] physics answer, but figured I'd share my practical experience.. pretty embarrassing, but hopefully you find it intact and can laugh about it!
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