Interesting test on barrel length and velocity

Discussion in 'Rimfire & Smallbore' started by butchlambert, Jan 27, 2018.

  1. butchlambert

    butchlambert Site $$ Sponsor

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  2. USMCDOC

    USMCDOC Silver $$ Contributor

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    So apparently speed starts to wane at around 24 inches on that barrel
     
  3. butchlambert

    butchlambert Site $$ Sponsor

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    It is getting faster as it is shortened.
     
  4. B23

    B23

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    I had two inches cut off my 17 WSM HB SS Bmag when I first bought it. I didn't chronograph it before I had it chopped back to 20in. so there was no base line with my rifle but I have chronographed it with my Magnetospeed since and it Avg. 2990 FPS with the 20gr ammo and the ES, for rimfire ammo, was surprisingly low. This isn't exactly a fair comparison but I've talked to multiple Ruger 77/17 WSM owners who chronographed their Ruger WSM's and those have 24in. barrels, every one of them got slower FPS speeds than I was getting and mine at 20in. shoots as fast or faster than those with factory length 22in. Bmags.

    I don't recall where but somewhere out there on the WWW is a chart that shows the results of someone doing this test with a 17 HMR and if I recall it pretty consistently gained speed with every inch cut off with it peaking velocity right around 19in.
     
  5. Tim s

    Tim s

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    22's are done with combustion about 16"-18" and then the slug is coasting to the muzzle.
    These tests have been around a longtime. I think the most comprehensive was by Frank Tirrel in Az a few years back.Unfortunately they miss the far larger question about 22 barrel accuracy usually concerning having the muzzle at a preferred bore dimension.
    For optimum accuracy, I'll take a longer barrel every time.
     
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  6. USMCDOC

    USMCDOC Silver $$ Contributor

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    Yes.. that is what i am referring to.. meaning that after 24 it is starting to slow down..
     
  7. butchlambert

    butchlambert Site $$ Sponsor

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    Do what? Read it again, it is speeding up as it is shortened. It will stop increasing at some point, but Saeed has not posted that yet as he is still cutting and shooting.
     
  8. USMCDOC

    USMCDOC Silver $$ Contributor

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    REad it again.. i am agreeing with you!
     
  9. mongo chicago

    mongo chicago

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    It makes sense. Once the bulk of the powder is burnt up,speed will not increase. If there is a significant amount of powder left burning, it will maintain the speed a little longer, but will not increase. After that point, speed will decrease no matter how long the barrel is. The longer sight radius will help in accuracy with iron sights.
     
  10. butchlambert

    butchlambert Site $$ Sponsor

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    Could be, but this is what I read
    " meaning that after 24 it is starting to slow down"..
     
  11. butchlambert

    butchlambert Site $$ Sponsor

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    Longer sight radius is usually handled with a bloop tube on a rimfire.
     
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  12. nakneker

    nakneker Gold $$ Contributor

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    Interesting, I never thought about the muzzle blast vs coasting out affecting a bullets exit before.
     
  13. Tim s

    Tim s

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    The theory is basically this: a 22 slug in a barrel initially sets up a lot of vibration. Thus tuners on BR guns.
    One of the things that some good gunsmiths feel make a good 22 barrel is one that allows the slug to "go to sleep" in the bore. More bore means greater likelyhood the slugs stop rattling around before the muzzle.
    One of the lovely aspects of trying to obtain precision with largely ninteeth century technology.
     
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  14. linekin

    linekin Silver $$ Contributor

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    So I'm guessing that the Lilja tight bores are just the opposite. Hoping that a tighter barrel stops all that rattling around??
    I have one on a sporter that shoots pretty well at the club level. It has about a 20" barrel, which the 10/22's guys seem to prefer.
    Keith
     
    Last edited: Jan 30, 2018
  15. Raythemanroe

    Raythemanroe Bullet Whisperer

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    Tim Tim Tim Timmay, the thread is about barrel length and speed..


    Ray
     
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  16. Tim s

    Tim s

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    Trying to politely answer to question posed in #12, there Ray Ray. I was done with the "greater question" post a bit back, a couple guys asked questions.
    They should have reviewed this type of process with you back 2nd or 3rd trip through 6 th grade, no?
     
    Last edited: Jan 30, 2018
  17. Tim s

    Tim s

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    What's tight these days? They're all pretty much tight.
    Was there a point in there somewhere ?
     
  18. linekin

    linekin Silver $$ Contributor

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    No point Tim. Just that you had mentioned a bore going to sleep.
    You said "Quote"More bore means greater likelyhood the slugs stop rattling around before the muzzle."
    So I was just wondering if Lilja was maybe thinking a bit differently? You having been here/done that I thought you might know. Thats all.
    Its a long winter.
    Keith
     
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  19. USMCDOC

    USMCDOC Silver $$ Contributor

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    i think that he was trying to relate maybe that yeah.. it is going to go to sleep... because it was a bore!
     
  20. hogpatrol

    hogpatrol Gold $$ Contributor

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    So after a certain point the bore is just creating friction and thus slowing the bullet down resulting in a lower MV?
    Is that the interpretation?
     
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