208 Amax's and tight bores do not mix

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by BountyHunter, Apr 29, 2007.

  1. BountyHunter

    BountyHunter Writers Guild

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    208 Amax\'s and tight bores do not mix

    Couple LR BR shooters are using the 208 Amax's and coming up with some interesting results. They have 6k of the best lots to test right now and an issue is being noted.

    The amax has a slight pressure ring and is slightly over .308. IT DOES NOT LIKE tight bores and this is being proven in 3-4 guns.

    One of the guys has a Broughton with a .3078 bore and it would not shoot them under 10". They lapped it out to .308 and cut off the end and recrowned. Shot several 5-6" groups last match with the same load.

    The Hart barrels are a true .308 and seem to shoot them well. Tim North of Broughton is making a special barrel with a bore of .308 exactly that will be on one of the test guns soon.

    Understand your bore and bullet dimensions and do not be afraid to change a bullet if it will not shoot. Many times it just might not be the barrel is BAD.

    BH
     
  2. davewilson

    davewilson Well-Known Member

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    Re: 208 Amax\'s and tight bores do not mix

    when they lapped out the barrel did it have any taper(smaller at the muzzle) or was it the same dia all the way?
     

  3. BountyHunter

    BountyHunter Writers Guild

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    Re: 208 Amax\'s and tight bores do not mix

    They had the same diameter and it even slightly belled at the muzzle which is typical of most none mftr lapping. Most gunsmiths just do not do enough lapping to be good at it like the mftr. That is why they cut off about an inch or so and recrowned it. Shooting 5-6" at 1k now, so it worked.
     
  4. eddybo

    eddybo Well-Known Member

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    Re: 208 Amax\'s and tight bores do not mix

    Well I actually hope they dont "fix" these bullets as they are shooting great for me just the way they are. Shot my best 500 yd group ever using these in my .300wby today. Either these bullets shoot better than noslers or all the time I am putting in at the bench is paying off. Guess I don't have a tight bore.
     
  5. BountyHunter

    BountyHunter Writers Guild

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    Re: 208 Amax\'s and tight bores do not mix

    the fix is not going to be on the bullets, rather they might soon start recommendind a certain bore/land to groove diameter.

    Just some info for guys that are jumping on them. Right now we know the early Broughtons might have problems with them but Tim is also making a true .308 bore barrel to test now.

    If you have problems with them, call the barrel mftr and see what the true land to groove diameter is. if it is under .308, then it is simply incompatible bullet/barrel combo and try another bullet.

    BH
     
  6. bailey1474

    bailey1474 <strong>SPONSOR</strong>

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    Re: 208 Amax\'s and tight bores do not mix

    I had a tight bore, 4 groove Lilja chambered in 300 RUM that shot the prototype bullets great. Never shot it on paper past 500 yds but hitting milk jugs 900+ yds was pretty easy.
     
  7. BountyHunter

    BountyHunter Writers Guild

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    Re: 208 Amax\'s and tight bores do not mix

    Bill

    I am talking the difference between 10-12" and 5-6" groups at 1000. If you are OK with 1 MOA at 1000 (most people are) then no issue, however if you are trying to squeeze the last bit of accuracy out, then you might or might not have a problem. If it seems that there is a problem, look at this first.

    BH
     
  8. bailey1474

    bailey1474 <strong>SPONSOR</strong>

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    Re: 208 Amax\'s and tight bores do not mix

    I see. I wish I would have shot them on paper @ 1000 yds. They did yeild several groups under 1.5" @ 400 yds w/some under 1". I think it is a very good bullet. Sure was hard on those milk jugs @ 900+ yds as well!!! Gotta love those polymer tips!!!
     
  9. BountyHunter

    BountyHunter Writers Guild

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    Re: 208 Amax\'s and tight bores do not mix

    By all indications it is a great bullet and Hornady is taking steps to put out a high quality product. that is why it was a surprise to have one gun shooting in the .5 at 1k and the other 1 MOA. Only difference was bore diameter. Hornady engineers are working with the shooters and testing this themselves to see what is the issue.

    Lapping increased the bore diameter and the second gun is not shooting in the .5 range at 1k.

    This was confirmed with another tight bore barrel, so the next step is a barrel with the pure .308 land to groove.

    Perfect example of why not every bullet shoots in every gun and why a good load for someone might be overpressure or terrible load for the next guy. Someone elses load "indicates" a powder and range of weight charges, bullet, primer combo for you to test only.

    BH
     
  10. BountyHunter

    BountyHunter Writers Guild

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    Re: 208 Amax\'s and tight bores do not mix

    [ QUOTE ]
    Lapping increased the bore diameter and the second gun is not shooting in the .5 range at 1k.


    [/ QUOTE ]

    Dummy, the correct word above is "now" instead of "not". Fingers faster than the brain this morning.

    BH
     
  11. JR

    JR Well-Known Member

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    Re: 208 Amax\'s and tight bores do not mix

    You said they cut an inch off the muzzle and recrowned. Perhaps the initial crown was the culprit? Perhaps there wasn't enough barrel cut in the first place to alleviate the bellmouthing caused by the initial lapping procedure?

    JR
     
  12. BountyHunter

    BountyHunter Writers Guild

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    Re: 208 Amax\'s and tight bores do not mix

    Doubt that was the issue, the barrel was a broughton and they are always lapped with a slight choke at the muzzle with the extra belled part cut off before that.

    BH
     
  13. JR

    JR Well-Known Member

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    Re: 208 Amax\'s and tight bores do not mix

    Well if it was relapped and chopped back before measurement of original, to the crown, any of Broughton's merits had been discarded. Doesn't quite sound like there is enough information there to disregard 'tighter' groove diameters, other than you found when two barrels have been lapped and cut back, they shot better. We're talking .0001" per groove making all the difference..I find it rather hard to swallow..Sounds more like the relapping, and cutting back ended up in a barrel which was a bit more uniform on release of bullet.


    JR
     
  14. JR

    JR Well-Known Member

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    Re: 208 Amax\'s and tight bores do not mix

    Hard to dismiss the results, no doubt, and I'm not trying to argue the fact. I'm arguin, but mostly with myself, hahah, just trying to get my head around it all. While at HS, we shot every rifle for group. I have seen lapping take many a barrel which shot 5/8-3/4" @ 100, to 1/4" and less, but I never figured opening the bore up made the difference. Usually the difference was the bullet was exiting the muzzle more cleanly, as there were so slight of imperfections at the break from muzzle due to dull or misaligned tooling during the crowning process. A guy could 'feel' what was affecting the exit of the bullet, even ever so slight, in the additional lapping session. When the obstruction was cleared, went back downstairs for group, and it performed as it should have.

    JR