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Can anyone explain "runout" and concentricity for me in plain English?
 

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Can anyone explain "runout" and concentricity for me in plain English?
Imagine the black of a target spinning with the X ring perfectly centered - that's concentricity.
Imagine the same thing with the center being the 8 ring - the distance of the wobble is runout.
That's a shooting analogy - hope it works for ya.
 

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'runout' happens when things that are supposed to be perfectly round aren't - e.g. a coffee can lid that is slightly 'egg shaped'.
If you roll a loaded cartridge on a flat surface there shouldn't be any wobble of the case body & neck or the bullet's point.

'concentricity' means that everything that is supposed to be in a straight line really is.
The centerline of the chamber straight with the centerline of the bore.
The cenerline of the cartridge body straight with the neck, and straight with the bullet.

With some rifles & bullets, if the bullet is slightly 'off center' in the cartridge it will remain off-center as it goes through the barrel, and that reduces accuracy.

Jay Kosta
Endwell NY USA
 

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Funny How Depending Upon What YOU Are Thinking About When A Question Is Asked...Impacts(pun intended! GITEN)Your Answer!

I have no idea what 'Wavekatcher' was really getting at, but as I just recently built a Suppressor(don't get excited! It's on an Approved Form ! GI6)...

I immediately thought...'THREAD Run Out'...meaning that the Barrel Threads Must 'peter out'--- End...so the Suppressor Stops Threading...
And Concentricity...meaning that not only the Bore of the Barrel, but also the Threads, and the Bore of The Suppressor, and the Baffle(s), and the End Cap...ALL Must be 100% Concentric...Lined-Up Perfectly...OR, Baffle-Strikes May Very Likely Result!

Anyway...Just Funny To Me How Different Words Have Different Meaning to Different Folks, Depending...

GITEN

CAVman in WYoming
 

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Concentricity means everything is in a straight line, resulting in a bullet that is pointing straight down the center of the barrel.

Runout is the measurement when something is off center, be it the inside of the case neck, outside of the case neck or even the ogive of the bullet itself.
 

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The O/P would have appreciated the answer 10 years ago when he posted it. He hasn't been on this forum since 2011.

I looked for a retard emoji, but there wasn't one.
 
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