New barrel, scope no longer centered.

Discussion in 'Scopes, Optics, LRFs, Spotters, BoreScopes' started by Drolds72, Jan 10, 2019.

  1. Drolds72

    Drolds72 Gold $$ Contributor

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    Have a golden eagle sitting in Burris xtr rings. Was a few clicks off the scope’s windage center with old barrel. Had equal rotation both ways generally for a no wind zero. Removed scope and rings and set aside to rebarrel. Get everything back together, but find I need to crank in about 20 moa of windage to center scope. Now sitting at 4 revolutions to the left, and only one to the right. Shot 4 groups this way and I was happy with them. Before the 4 groups, I had it sighted, but went home removed scope to check everything and reinstalled it. Nothing looks out of place. Removed and mounted while using a laser, and it is coming back to same spot. I had flown with rifle right before i rebarreled. Can the internals get knocked off that much? Or do I have something else going on?
     
  2. SSL

    SSL Gold $$ Contributor

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    New barrel, new scope settings. Each barrel is an individual depending on stress and other issues related to the boring and chambering process. Assuming your accuracy is acceptable, probably better off shimming rings or bases to center the crosshairs so you have relatively equal adjustments in all directions.
     
  3. gunsandgunsmithing

    gunsandgunsmithing The best tuners and wind flags on the market Gold $$ Contributor

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    Barrels ain't straight..none of them. No worries, just adjust the scope and go shoot.
     
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  4. Drolds72

    Drolds72 Gold $$ Contributor

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    I knew it would be off some, but doesn’t 20 Moa at 100 yards seem excessive?
     
  5. gunsandgunsmithing

    gunsandgunsmithing The best tuners and wind flags on the market Gold $$ Contributor

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    It's more than typical but how does it shoot? From your post, I take it that the receiver wasn't touched. That leaves barrel, barrel/action abutment, scope, bases/rings and bedding, as well as harmonics, that can possibly affect poi. Some smiths index barrels and some don't. Some do it one way and some another. I agree that it's more than you will typically see but all that matters is the target.

    I've chambered barrels that are pretty much spot on with different barrels for poi. Others, may be off a bit...but I've won br matches switching between them.
     
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  6. savagedasher

    savagedasher

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    If that far off at 100 what will it be at 1000
    Everyone one I hav different barrels for is never more the 2 inches
     
  7. gunsandgunsmithing

    gunsandgunsmithing The best tuners and wind flags on the market Gold $$ Contributor

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  8. gunsandgunsmithing

    gunsandgunsmithing The best tuners and wind flags on the market Gold $$ Contributor

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    The same MOA. What you might give up is scope travel in the vertical plane. I didn't see 1000 yards mentioned. Not that it matters, but not everyone does that stuff. This could be a hunting rifle, where most people may as well be shooting at a barn at 300 yards.

    Not saying that's the op...just saying there are different requirements in equipment. IOW, if the longest shot he may take is 300, why worry about lost elevation travel...if it shoots well.
     
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  9. mr45man

    mr45man Gold $$ Contributor

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    Shoulder, receiver face or crown is totally wrong. Period.
     
  10. savagedasher

    savagedasher

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    I thought he said windage Sorry
     
  11. Drolds72

    Drolds72 Gold $$ Contributor

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    7CC68EF1-4FFD-43BB-8A12-AD61ECF1F243.jpeg
    This is my f class rig. Borden brm action, non bedded. Gunsmith clocked barrel to 12. Pic below are the first 2 groups out of it, fireforming 6br to 6bra. So I think it’s gonna shoot. Planning on using this for midrange, and the 284 barrel I had done for long range. Haven’t shot that one yet. Oddly, the vertical was spot on, as I was using my old 6br load to fire form with. I just seem to have lost 15 moa of windage in one direction.
     
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  12. gunsandgunsmithing

    gunsandgunsmithing The best tuners and wind flags on the market Gold $$ Contributor

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    Not entirely but virtually impossible...if you do the math.
     
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  13. boltfluter

    boltfluter Gold $$ Contributor

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    You might try reinstalling your old barrel as a reference, to see if your zero is somewhat close to before. May help with diagnosis if there is a scope issue. Just a thought.:D:D

    Paul
     
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  14. Alex Wheeler

    Alex Wheeler Gold $$ Contributor

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    Math for those thinking barrel indexing. Assuming a barrel shoots where it points, it would take .156" of muzzle off set on a 28" barrel from centerline to be 20 moa. Thats .312" muzzle TIR in the lathe. Worst TIR I have ever seen is in the .050" range.
     
    Last edited: Jan 11, 2019
  15. dkhunt14

    dkhunt14

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    Did you put the rings on in opposite direction? Matt
     
  16. shoot4fun

    shoot4fun Gold $$ Contributor

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    I've only witnessed this example once in my lifetime and may not have believed it if I had not seen it. A good friend (passed on now) bought a new Savage Model 12 (forgot particular model but heavy fluted barrel and laminate stock). In our initial trip to the range he took handholds made up with the same lot of powder, primer and brass. The only variable was one group loaded with a Sierra 65 grain varmint bullet and the other with a Hornady 65 grain varmint bullet. After sight-in with a few rounds of factory ammo he fired a group with five rounds from one of his handholds. It printed a very small (one tiny hole) group at 100 yards and dead center of the target. Even better, it repeated with the second five. We changed out the target and then things got interesting.
    Moving on to the other brand bullets, he fired a round at a the target. I called a clean miss. "NO WAY" he shouted. I carefully scanned the target with my spotting scope but no hole did I see. The second round was launched; again I called a clean miss. The third round I watched merely for signature from where the round would hit the berm. To my surprise, it was well (about 24 MOA) right of where the groups had been with the other bullets.
    We went down with another target, placed it to the right of our original, and proceeded to record a nice tight (almost as tight as previous) group. He aimed at the target on the left and grouped on the target on the right. OK, I said, maybe that scope is bad.
    We shot another group, going back to the original ammo, and found it to strike in the original spot as before and with virtually the same groups size. Calls to both Hornady & Sierra Tech Support got us the same answer. An exaggerated display of just how one barrel's harmonics can be changed by the bullet.
    I would think, in fact I know from my experiences, that changing out from one barrel to the next (both 6BR on my BAT MB long-range BR) can move my POI by over two feet to the left at 500 yards. They are the only two of many barrels I own that this occurs with.
     
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  17. highplainsdrifter

    highplainsdrifter

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    I actually had a bent barrel. It was a long thin barrel on a .222 Remington. Got bent during a move. Was perfect before, then after the move, could not put rounds on the target at 50 yards. Went though the processes with the base, rings, scope, etc., then took the gun to the gunsmith and found that the barrel had gotten bent in the move. Replaced the barrel and rifle shot dead on again. Barrels can get bent.
     
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  18. Ned Ludd

    Ned Ludd Silver $$ Contributor

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    20 MOA seems like an awful lot for simply having the rifle re-barreled. In fact, I'd say that's HUGE. Before getting too alarmed however, I'd do a few quick tests first to make sure it wasn't something else, such as A) re-mounting the scope, B) checking to make sure exactly where the reticle is located within its total windage (horizontal) travel range, C) as mentioned above, you could also put back on the old barrel and see if the zero goes back to what it was. Bottom line is that 20 MOA windage is almost all the windage adjustment available to your scope in one direction (45 MOA total, 22.5 MOA either direction). That is simply going to be unacceptable for shooting in competition, and if it were me, I'd like to know why, and whether it was an issue that could be rectified.
     
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  19. Drolds72

    Drolds72 Gold $$ Contributor

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    All good stuff. I am going to work through this methodically and see if I can find the cause of the shift. The 20 moa shift was from the last known wind zero, not the optical center of the scope. Going to slow down, back up, check everything and report back.
     
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  20. Ned Ludd

    Ned Ludd Silver $$ Contributor

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    That's always a good approach. I would also add for anyone that may not routinely do so that keeping meticulous records of scope settings for various distances and wind conditions can be a useful resource when problems such as this are encountered.
     
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