Tubbs final finish :-(

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by sendero72, Oct 25, 2012.

  1. sendero72

    sendero72 Well-Known Member

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    I posted about the Tubbs Final Finish months ago and finally got around to firing lapping 2 days ago. The barrel is slick as a whistle, but none of my former load will "hit the backside of a barn". The rifle is a 243 Savage model 11, 9 1/4 twist, 22" . The funny thing is that the last 5 rounds of the final polishing bullets shot a group just under .5 MOA @100 yds. I thought this is great! The bullets in the kit are 107 gr Sierra match which I assume are used because of a long surface bearing for greater fire lapping. In theory the 9.25 twist should never have stabilized the 107gr to start with. Anyone got any suggestion on loads or as to what has happened to the barrel. My former loads were the 95 gr BT's and the 105 Amax. Help needed!!!!!
     
  2. benchracer

    benchracer Well-Known Member

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    If you used all five sets of bullets, instead of just the three finest grits, my guess is that you moved the throat forward some.

    I would start by determining the COAL that touches the rifling with your desired bullets. Then load 5 rounds at max COAL, 5 more at max COAL minus .040, 5 at max COAL minus .080, and 5 at max COAL minus .120. This test comes from Berger's website and I have found it to work with every bullet I load.

    Most likely, one of those seating depths will show good accuracy. You can fine tune from there if you feel the need.
     

  3. sendero72

    sendero72 Well-Known Member

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    I did not think about possibility of the throat movement. I'll have my Hornady Comp gauge on it in the morning.


    Thanks
     
  4. bbutturff

    bbutturff Well-Known Member

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    I agree. +1 :)
     
  5. Wile E Coyote

    Wile E Coyote Well-Known Member

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    I've used a Tubb Final Finish kit on two rifles over the past couple of years. A Savage 99 in .308 Win, I only used factory ammo in. The rifle went from a 1 1/2+ MOA off a sand bag to a minute at 100 yds.

    The second rifle was a new Remington 700 in .223. After breaking it in, I developed a load that would shoot about 3/4 MOA but I couldn't get it any better. Curiosity finally got me and I fire lapped the barrel using only the 3 finest grit bullet sets in the kit. I did have to re-work the original load a bit. Powder increased very slightly and the 52 gn Sierra MK is seated closer to the lands. The gun will now shoot under 1/2MOA and often better when I do my part.

    Would I use it again? Yes, in the right situation such as a factory barrel I want to shoot better. You would, however, have to twist my arm hard to get me to put it through any of my match grade barrels. Maybe when I get one that starts to lose accuracy I'll try it.

    This was my experience with the product. Hope it helps.