Sinclair Concentricity Gauge
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I went for .002,they are kinda finaky to adjust,but i drilled hole in my table and tweak a bit and gain.Then in my ammo box I mark one end A. If they are farther out I circle primer w/sharpie and bust rocks at LR with them.Funny is that I usally hit way out.
One of the best things of a run-out gauge is that it allows you to measure for run-out at each step of your reloading process . This allows you to see where the run-out is coming from and allows you to correct it. Run-out can come from several different processes.
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I just watch a couple of videos but I am so open to learning
A few years ago I read that for hunting at moderate range ( 0-350 yds) .005 run-out was sufficient. For varmint hunting or long range big game hunting ( over 500 yds ) .003 or less and for comp shooting as close to zero as you can get. I think this is fairly true. JMO
Mikecr
Well-Known Member
No, the affects of runout do not manifest as linear. Given this, for as many who think runout matters, their are those who don't. An abstract.
Runout can matter, but not for the reason written about in gun rags, and most books. These describe runout as a concentricity(misnomer for eccentricity) issue, causing chambered bullets to point off-axis with the bore, causing degraded engraving and release.
That's dead wrong, and easily proven so.
The truth is that runout (TIR)(not eccentricity) matters only when exceeding chamber clearances for it.
This, causing chambered pressure points, affecting barrel vibrations. If you were to press against your barrel at the chamber in the middle of a group, you could simulate this, likely seeing thrown shots.
To manage TIR, and stay clear of this, you should know your chamber clearances.
Just keep your TIR within this, anywhere.
It's not just necks, or bullets. It's the entire cartridge.
The root cause of runout is sizing of thickness variance. More of either = more TIR.
Runout can matter, but not for the reason written about in gun rags, and most books. These describe runout as a concentricity(misnomer for eccentricity) issue, causing chambered bullets to point off-axis with the bore, causing degraded engraving and release.
That's dead wrong, and easily proven so.
The truth is that runout (TIR)(not eccentricity) matters only when exceeding chamber clearances for it.
This, causing chambered pressure points, affecting barrel vibrations. If you were to press against your barrel at the chamber in the middle of a group, you could simulate this, likely seeing thrown shots.
To manage TIR, and stay clear of this, you should know your chamber clearances.
Just keep your TIR within this, anywhere.
It's not just necks, or bullets. It's the entire cartridge.
The root cause of runout is sizing of thickness variance. More of either = more TIR.
Mikecr
Well-Known Member
The Sinclair V-BLOCK type runout guage is excellent because it conceals nothing.
Just overlook the term 'concentricity', as it does not directly read eccentricity, nor show a state of being concentric.
But ammo that is STRAIGHT (low in runout) happens to be concentric as well.
The best we can do is make straight ammo. This will chamber without bind.
Just overlook the term 'concentricity', as it does not directly read eccentricity, nor show a state of being concentric.
But ammo that is STRAIGHT (low in runout) happens to be concentric as well.
The best we can do is make straight ammo. This will chamber without bind.
So back to the original intend! Eccentricity of bullet to case. 1) How much is too much for hunting under 500 yards. How is over 500 yards (all my rifles are hunting, I don't do competition shooting)
How can I correct eccentricity after a bullet is seated?
I should probably check the bullets before loading to see how far out of "round" they are
How can I correct eccentricity after a bullet is seated?
I should probably check the bullets before loading to see how far out of "round" they are
Mikecr
Well-Known Member
You're seekin something other than understanding.
"IF" you can get down to under .001," why not. I keep mine <.002" and use Hornady's concentricity case if they need adjustment.
nksmfamjp
Well-Known Member
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Measured at the bullet tip, I'm trying to get under 0.003", but under 0.008" seems to shoot within my ability. I tried bullet tip adjustment
Measured at the case mouth, I'm shooting for 0.002". I get that with most dies when things are setup right. Be careful with this measurement. On std dies, this is best measured as a transfer measurement at the bullet close to the mouth.
Be cautious with tools like the Hornady tool. They are measuring with the wrong datum scheme. It is like measuring down the edge of a board, marking, then setting up the table saw to that mark. If the board is not square, your cut will be off.
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For truly concentric ammo you would want to ID turn the necks on those fire formed cases, fixturing off the OD of the case body. Like the new idod neck turning tool. Then use a neck bushing to size the neck.
That then brings up the problem of clearance between the loaded case and chamber; what good is a concentric cartridge if you can't hold it concentrically to the bore.
Thanks Ed, It is interesting, but I have the Sinclair. Definitely educational though
