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POI shift with chopped barrel.

Discussion in 'Gunsmithing and Repairs' started by vaeevictiss, Oct 28, 2012.

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  1. vaeevictiss

    vaeevictiss Member

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    I recently had the barrel on my 700 sps .308 chopped and threaded from 26" to 22" and topped with a break. Now I understood I would have to resight the scope with this kind of work, but is 9" to the right (@100yds) normal? It seems a bit extreme. My scope was able to do it, but I'm concerned about longer ranges.

    Could the crown have gotten knicked or the barrel not be mounted straight?
     
  2. GCBurner

    GCBurner Member

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    Shorter length changes the barrel harmonics, and possibly the bedding in the stock has changed from removing and replacing the action while it was being worked on.
     
  3. Birdhunter1

    Birdhunter1 Member

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    Did you remove the scope and put it back on? My rifle loading mentor had taught me that 0.001" of movement on your scope in the rings/mounts/etc equates to about 1" at 100 yards in impact.
     
  4. creeper1956

    creeper1956 Member

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    You didn't say that it's not grouping... so I assume it's grouping as well or better than it did at original length. If it's not grouping, you most definitely should have mentioned it.

    Based on the above assumption, the crown, the brake and the threading job done to fit them are probably fine. If the crown was incorrectly cut or the brake was not concentric, it would, in all likelihood, have a negative effect on accuracy... not a dramatic POA/POI change alone. Makes sense?

    So... what's left?
    • The re-installation of the barrel. If the barrel was removed and reinstalled only, with no other changes and the barrel was returned to it's original clocking... then I can't see that as a cause either.
    • Action and stock/bedding. Unknown.
    • Scope and/or scope mounts and base. Unknown.

    If it's not grouping on the other hand... :rolleyes:

    C
     
  5. vaeevictiss

    vaeevictiss Member

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    Yea I didn't have time to shoot any groups with the bad weather here but I will this weekend. I just shot a few rounds to see how the new brake felt and noticed it was way off.

    Sent from my Galaxy Nexus using Tapatalk 2
     
  6. Double Naught Spy

    Double Naught Spy Sus Venator

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    So the barrel was chopped and a brake put on it. Okay. How about the crowning?
     
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