Headspace for off the shelf ammo - 6.5 creedmoor

Discussion in 'Gunsmithing' started by Mram10us, Oct 26, 2019.


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  1. Mram10us

    Mram10us Well-Known Member LRH Team Member

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    Built a 6.5 creedmoor today for using stock hornady match eld 140s. Thought I’d show how I headspace for off the shelf ammo. I obviously didn’t invent this. Saw a good gunsmith do this and stole his idea :) Hope it helps someone. Start the video at 4 min mark.


    Update: I added the video to a well-known Gunsmith so people would stop questioning the technique. Hopefully he can put the point across better than I could.

    Update 2:
    Here are targets from the first 40 shots with hornady match 140 ammo at 200yds
    CC06AE32-00B3-4645-B1DB-D99087E8AC33.jpeg 416FC449-7F94-4D1B-A264-A7142F5027A9.jpeg
     
    Last edited: Nov 6, 2019
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  2. MNbogboy

    MNbogboy Well-Known Member

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    May work for that box of ammo but might not the next. Another brand may not fit either.
    Hope that guy wasn't thinking about reloading them, good chance won't be able to FL size them down enough to fit in the same chamber.
    Saami specs allow the case to be waaay short of chamber/die specs.
    To each their own but to me that looks like trouble in the making.
    My .02
     
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  3. Rhovee

    Rhovee Well-Known Member

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    I have this done all the time. Not any issues.
     
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  4. MNbogboy

    MNbogboy Well-Known Member

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    Ive done it with fired & sized cases. I have five 6.5 CMs with virtually the same headspace all within a half a thou. Makes sizing easier with fewer setting changes.
    New ammo however can be .008 or more short of saami headspace gauges. Setting headspace at minimum with the gauge is enough to cause sizing issues with some FL dies. Many have struggled with sizing problems derived from "short" headspacing.
     
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  5. Barrelnut

    Barrelnut Well-Known Member

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    Agree with MNbogboy.
    This is just a bad idea for many reasons.
     
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  6. Mram10us

    Mram10us Well-Known Member LRH Team Member

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    As I said, I built this rifle for that ammo. 2 boxes cycled thru just fine. If I decide to reload and the fl die is a touch long, I’ll either trim the die or the shell holder. All easy to deal with :)
     
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  7. Mram10us

    Mram10us Well-Known Member LRH Team Member

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    What reasons?
     
  8. Rhovee

    Rhovee Well-Known Member

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    Both my 300 and 338 Norma are .009” short. I send cases I’m going to use to gunsmith so he can head space off of them. Usually they end up at zero headspace. I have had to shave .005 off a shell holder in the past. I started doing this because some cases had .009-.011 growth on first firing. Early head separation. Difference in velocity. Not worth messing around
     
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  9. MNbogboy

    MNbogboy Well-Known Member

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    Creating false shoulders in the neck of new brass is an alternative method of preventing premature head separation caused by short cartridge base to shoulder lengths of new brass.
     
  10. aushunter1

    aushunter1 Well-Known Member

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    I wouldn't base anything on factory ammo, even match ammo.

    I relatively recently bought 3 boxes of 20 Federal factory ammo for a 300wsm that 50% would not even chamber!!

    Ok make the rifle to your parameters but don't expect it to work 100% f the time.

    At least if you reload to can make the brass fit the chamber by fire forming & adjust your sizing dies accordingly.
     
  11. Revolting Peasant

    Revolting Peasant Active Member

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    I have used basically this method before with Savages and the barrel nut to get a minimum sized chamber. If it ends up to tight with other boxes of ammo just take it apart again and adjust out a couple of thousandths.
    With a no nut barrel, prob just run a finish reamer in another couple of thousandths and lengthen the chamber if it became a problem later.
    It’s not rocket science or sending a man to Mars.
    Way better than an excessively long chamber. RP
     
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  12. 5.56×250

    5.56×250 Well-Known Member

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    I headspace my recent remage 6.5 creed using the longest cased factory ammo out of 5 different brands I had on hand. I put 2 pieces of packing tape ( measuring .003 total ), trimmed to not overhang the side of the cartridge head, on the case and screwed the barrel down till it snugged against the shoulder ( with the ejector removed from the bolt /rem 700). New Petersen brass grew .0015 when fired with my handloads with the chamber set that way. I'm calling it a win.
     
  13. Mram10us

    Mram10us Well-Known Member LRH Team Member

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    Added range day
     
  14. Mram10us

    Mram10us Well-Known Member LRH Team Member

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    You obviously have no idea what you are talking about or you would give me and the other Gunsmiths that use this method a good reason. It isn’t saami, however, it has been proven safe. Just so you know, the go and no go worked as advertised;)