22LR Headspace

Discussion in 'Rimfire & Smallbore' started by shoot4fun, May 13, 2019.

  1. shoot4fun

    shoot4fun Gold $$ Contributor

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    I have two 22LR bolt guns, one a CZ455 with Federson barrel and one Vudoo with Bartlein barrel.
    I installed the Federson on the CZ455, along with a Glades bolt handle, and the Vudoo barrel (I assume) was installed by Vudoo. I have the tools to check and sort ammo by headspace but how do I know where the headspace on my rifles is set?
    Also, what should the ideal headspace be for match grade 22LR ammo?
     
  2. Tim s

    Tim s

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    You don’t need to waste time sorting high grade ammo.
    You check with a set of gauges.
    I’d suspect the Vudoo is set @.043”
     
  3. 243winxb

    243winxb

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    Last edited: May 13, 2019
  4. Mikemontminy

    Mikemontminy

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    9410276B-60C8-4DF5-9057-2B5DE802A3E3.jpeg To check your headspace take a fired 22lr case and anneal the brass so it’s soft. Then place the rim over a 1/4” nut or washer. Use a punch inside the case to form a bulge like in the picture. Next chamber the case in the rifle you want to check headspace on. The rim will squish down and can be measured with your tools that you already have. Don’t be afraid to over anneal the case.
     
  5. shoot4fun

    shoot4fun Gold $$ Contributor

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    I feel it is just the opposite. Don't sort any 22LR ammo EXCEPT high grade match ammo.
    I can't vouch for the scientific authenticity of my testing but I do see a difference in most brands of match ammo between sorted and unsorted of the same lot.
     
  6. Tim s

    Tim s

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    Yeah, this has been beaten to death on rimfire forums, usually by guys that never shoot in matches.
    Nobody does this.
     
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  7. shoot4fun

    shoot4fun Gold $$ Contributor

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    OK. I don't weigh primers but please humor me on this one. After all, I have a really cool little tool for it. ;):D
     
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  8. theallcineyes

    theallcineyes

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    People do not realize that rimfires have higher pressure than many centerfires. They assume because they are "weak" they do not have much pressure.

    SAAMI MAP for 22 Short, 22 Long, 22 Long Rifle, 22 Magnum and 17M2 is 24,000 PSI as measured by the piezoelectric method. 17HMR SAAMI MAP (max average pressure) is 27,000 PSI.

    These pressures are higher than many of the older (and some fairly new) centerfire rounds.

    The other reason headspace is very important in the 22 LR and others is because it has an adverse effect on accuracy to have anything but minimum headspace.
     
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  9. Hi-NV Shooter

    Hi-NV Shooter

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    By how much of a difference will it start to effect accuracy? meaning if 0.043 headspace is standard for a match quality rifle, would I see accuracy fall off at 0.044, 0.045, etc. ?
     
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  10. shoot4fun

    shoot4fun Gold $$ Contributor

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    My thinking is that sorted 22LR ammo will be much like having the proper seating depth for center fire ammo. In other words, keep that number the same by sorting ammo into like lots.
    I know without a doubt that both of my rifles are within headspace specs but was wondering if accuracy is in the reamer spec, the headspace, the rim thickness or some other factor I can't fathom.
     
  11. Someoldguy

    Someoldguy Silver $$ Contributor

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    Are you sorting by BTO? Then yes, I think that is comperable to checking seating depth.
    However, if you are checking rim thickness, then I think that is more aligned with case length.

    Perhaps I'm off in the rough. (?)
     
  12. shoot4fun

    shoot4fun Gold $$ Contributor

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    It is my understanding that rimfire cartridges headspace off the rim. If the difference in thickness is minimal, say +/-.001" then the relationship of the bullet to the rifling should be virtually the same (at least that is what I am thinking). Maybe, more importantly in my mind, the ignition of the primer/powder will be the same from shot to shot and help minimize the dreaded flyers 22LR shooters curse.
     
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  13. theallcineyes

    theallcineyes

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    i think you will achieve more accuracy at 0.047.
     
  14. Someoldguy

    Someoldguy Silver $$ Contributor

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    I think both rim thickness AND BTO are of equal importance.
     
  15. Tim s

    Tim s

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    Yep, so do I, it was important to do........about 20 years ago.
     
  16. 1911nut

    1911nut

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    I’ve used the Neco base to ogive gauge to sort Center-X. I’ve found variation in length of 0.005”.
    Initial testing of sorting out the longs and shorts and shooting rounds of all the same length has reduced the 50 yd group size of Center-X in my rifle. Yeah I need more testing.

    It’s another tool to mess with.


    D5C48BC2-0471-4B9C-8F6D-16728F56EF63.jpeg
     
  17. Tim s

    Tim s

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    Really??? You might want to do a search on the extensive tests done and published by Bill Calfee who has made countless world record holding rifles which absolutely disproves this. He went out several thou over normal .043” with no adverse effects.
     
  18. Tim s

    Tim s

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    This is another deal entirely, but can be potentially useful.
    I don’t know about that gauge but the ones I know about, the one I have, is made on a section of barrel cut with the reamer used on my barrels.
    Some ammo lots can vary by 10 thousandths, and some guns like short, some longer.......seems to be barrel/chamber specific.
     
  19. lloydx2

    lloydx2

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    I have measured rim thickness and bullet diameter on some really expensive $110 (match ammo)
    the bullet diameter varied as much as .0007 in the same lot. I have not shot any of it sorted out
    with lab radar to see if it makes a difference in velocity I will say the ammo doesn't shoot
    well in my Vudoo. Lots of vertical. The 60 dollar SK match out shot it. Seems like a game the manufactures play.
    Once they have everyone hooked on it they lower the QC. All bullet measurements were done on a .00000 Mitutoyo
     
    Last edited: May 15, 2019
  20. shoot4fun

    shoot4fun Gold $$ Contributor

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    This is what I found. It isn't so much that one sorted group is better than another (same lot) but that each will outshoot like ammo that is unsorted.
     
    Last edited: May 14, 2019

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