Dwell Time

Discussion in 'General Firearms Discussion' started by The_Rifleman, Aug 11, 2017.

  1. The_Rifleman

    The_Rifleman Well-Known Member

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    Do these results fit your understanding of "dwell time."



    The top guns have their sights heights set parallel to bore; and the bottom guns rear sights are .024" higher.
    The velocities are virtually the same.from 830 to 860, give or take 15fps.

    Even though the bottom gun kicks much more than the others, it hits much lower. The top has a longer barrel, and very little recoil; it hits much higher.
     
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  2. Shanghai

    Shanghai Well-Known Member

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    Your demonstration did a good job of illustrating and understanding the affect of dwell time. Good job.
     
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  3. carver

    carver Moderator Supporting Member

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    I think we all know that dwell time does exist, but you did a good job demonstrating it. Thanks.
     
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  4. The_Rifleman

    The_Rifleman Well-Known Member

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    Here is another video on it. I am addressing others in the video, not very friendly people; so if I sound condescending, I'm simply clubbing those people with data.



    I thought these results and conclusions would be welcome here.

    The more I do these tests, the more I understand ballistics. I predict the snub-nose handgun's slower, heavier bullets; will start impacting higher at 60 yards. That's where I'll test tomorrow.
     
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  5. CCHolderinMaine

    CCHolderinMaine Well-Known Member

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    Interesting stuff...
    I opened the thread thinking it was a discussion on how long the points were closed.
    Ooops :)
     
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  6. Firpo

    Firpo Well-Known Member Supporting Member

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    Me too CCHolder.
     
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  7. 76Highboy

    76Highboy Well-Known Member

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    In firearms, dwell time is the amount of time it takes the projectile to exit the muzzle. On my fixed sight SP101, I can change my point of impact by changing the load. By reducing the load (lower velocity means more time in the barrel) or use a heavier bullet (more time in barrel I can rise my point of impact.

    This is how I hit a pop can at 100 yards with a fixed sight revolver. Make the dwell time match where I want to hit.

    The video shows exactly how it works. This is why when a person is hitting a pop can at 10 feet, they have a hard time hitting it with different barrel lengths because we tend to shoot by line of sight. Dwell time says otherwise.

    Good video.

    Highboy
     
    Last edited: Aug 13, 2017
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  8. Shanghai

    Shanghai Well-Known Member

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    Hey, you might be on to something. It never crossed my mind to use a dwell meter for checking barrel dwell time.:)
     
  9. The_Rifleman

    The_Rifleman Well-Known Member

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    My prediction was a little off, I will test again at 70 yards tomorrow; just to be sure.

    As a side note: The 2.5 inch revolver with the 158gr 830fps bullets, hit about 2 inches high at 25 yards, and about 3 inches low at 60 yards. That is a lot flatter shooting than most would think.

    I'm starting to like that little gun, and have a better appreciation for 38 specials too!
     
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  10. The_Rifleman

    The_Rifleman Well-Known Member

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    I know this isn't new to many of you, but this video displays how dwell time seems to work differently with pistols, as opposed to revolvers.

    I did a test with a 1911 9mm, and it worked like this 45 1911, but the rounds weren't precise so I think I need to reload for it to get a compelling result.
     
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  11. sharps4590

    sharps4590 Well-Known Member

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    An interesting thead!! I never spent the time studying the interior and exterior ballistics of handguns that I have with rifles although the concepts should be the same. My understanding of "dwell time" was always applied to BPC bullets and how long they stayed in contact with a steel target at distance. A long, heavy for caliber bullet has a longer dwell time in contact with the target than a shorter bullet which explains why the bigger bullet had an easier time knocking over distant targets. As with so many terms used in discussing firearms it appears "dwell time" has more than one meaning.
     
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  12. carver

    carver Moderator Supporting Member

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    While I like watching Rifleman's videos, and I like learning anytime, my approach to pistol accuracy is not scientific. I set up an 8" paper plate. I start close with any pistol, no matter the barrel length. Then start moving back from the target. When I reach a distance that I can no longer keep all shots on the paper plate, then the last distance I could, is the limit of my range for that pistol. If I want to shoot further, then I have to practice with a given hand gun until I can keep all shots on the paper at the new, longer, distance.
     
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