runout created by bullet seating

GW Hunter

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Joined
May 2, 2015
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465
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Orangevale, Ca
Just resized a box for my 7mm weatherby. Annealed before resizing. Did every step meticulously. The runout on the neck on every piece of brass was between 0 and .002. Reamed the brass with a VLD reamer and seated 150gr TTSXs with a Forster ultra seater. Used a nice steady stroke and ended up with (9) at .002, (3) at .003, (4) at .004 and (4) at .005. What can I do to try and prevent this next time?
 
I guess I should have checked the neck runout before posting... I just did and the necks are still straight as they were before seating. Is my problem related to case neck thickness? I have never turned the necks.
 
Is my problem related to case neck thickness?
Most likely. How did you size the brass? Generally, when you seat a bullet in annealed brass, it's soft enough for the bullet to push the differences to the outside. It then shows up on your gauge. It's not gonna be hurting accuracy until it's more than 4-5 thou, unless you're a helluva shot.
 
I do not recommend reaming inside necks. If not perfectly cut, you will lose concentricity. Yes, you need to turn the necks. Despite all the proper steps, you will still have some runout. On a loaded round, I think .002 -.003 is OK.
Reloading
 
Most likely. How did you size the brass? Generally, when you seat a bullet in annealed brass, it's soft enough for the bullet to push the differences to the outside. It then shows up on your gauge. It's not gonna be hurting accuracy until it's more than 4-5 thou, unless you're a helluva shot.
Regarding the bullet pushing the differences to the outside of the neck.... The necks are still <.002, but some of the bullets are out up to .005. Would this require reaming to correct?
 
GW, did you ream the necks with a reamer or chamfer the necks with a VLD chamfer tool. Big difference.
 
I am on here to learn from some of the really sharp guys and gals on here but I turn my necks just enough to take the high spots off. It may not clean the neck up completely but maybe 75-80% range (maybe .0005-.001 off the diameter). Doing this really helped my groups and runout.
I do have one tight neck that I have to turn to a specific dimension.
 
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