Concentricity gauges and neck tension

[garandman]

Even with a strong in line ejector spring pushing the case shoulder into the chamber shoulder before firing?

What about a 2.5 ounce firing pin moving 20 fps pushed by a 25 pound spring force?

I have no idea. I suspect every rifle will be different, and no universal answer is possible.

 

[dmoran]

@Bart B.
Instead of beating around the bush (again) to dramatize your input , why don't you just spit it out already...lol

 

[Bart B.]

@Bart B.
Instead of beating around the bush (again) to dramatize your input , why don't you just spit it out already...lol

Because I don't think I'm the only person who knows what cartridge-chamber issues actually position the bullet relative to the bore before and when the round fires. I'm encouraging others to figure it out themselves.

Your snide remarks don't contribute anything worthwhile.

 

[dmoran]

@Bart B.
Your continues dramatizing, leading up to your broken record response that you've flooded the forums with repeatedly, that is hardly even on topic ("Concentricity gauges and neck tension") doesn't contribute much of anything, and hijacking (an aspect you & fguffey are legends at).

 

[Bart B.]

@Bart B.
Your continues dramatizing, leading up to your broken record response that you've flooded the forums with repeatedly, that is hardly even on topic ("Concentricity gauges and neck tension") doesn't contribute much of anything, and hijacking (an aspect you & fguffey are legends at).

I'm not impressed by your blatant ignorance. It's typical of unqualified forum moderator wannabes who, in reality, are ignoratiolinguists.

 

[garandman]

Im with @dmoran on this. I wish you would just make your point. ANY point. Im listening...

 

[Capt45]

ignoratiolinguists Not sure that's a word, but I like it, a lot!

 

[mikecr]

I believe bullets on release are pretty much aligned no matter what we do. Hell, FL sized ammo sloshing all over in a loose chamber, and seated off the lands(OTL) can shoot really well. The self aligning with striking theory, I doubt, at least with cartridges having shoulder angles at 30deg+. Maybe with cartridges having way lower shoulder angles. I suppose they could wedge in, and then I can't see this as 'good' for anything.
Folks have tested best/worst runout and found that it had to get pretty ugly before affecting results. Some see clear affects early on. The difference I believe is not how bullets are aligning.

I think the difference is in cartridge-chamber interferences presenting with crooked ammo. There needs to be some clearance or straight enough ammo, to prevent chambered pressure points (points of interference). These pressure points would be like abstract pressing against the barrel(around chamber) with a thumb, on firing, opening grouping.

I suspect case runouts exceeding chamber clearances as the line crossing, where runout does actually affect results.
If you're seated in the lands(ITL) and your throats are fairly long and no more than 1/2thou over cal, then your bullets are pretty much aligned with the bore no matter what kind of case runout or alignment falls behind that. And even here, I think that if you introduce cases with runout exceeding chamber clearances, your grouping will still step change for the worse.
Just a theory. I have no reasonable way to prove it myself..

 

[Bart B.]

My point is the case shoulder centers in the chamber shoulder before the round fires from ejector or firing pin force. There's typically a little clearance around the case body to the chamber except at the case pressure ring where it's usually pressed against the chamber by the extractor. A perfectly straight cartridge with its pressure ring off center .001" against the chamber wall will have its bullet tip about a third to half that much off bore center in the opposite direction. 100% repeatable across all such rounds.

No cartridge runout gage holds the cartridge that way. Its front reference should be a hole whose diameter is where the chamber headspace datum is. The case pressure ring (we hope is not too much out of round) should rest in a V block. Dial indicator should touch the bullet opposite from one pressure ring touch point in the V block. And some standard distance from the case shoulder datum.

This way, the same conditions and standards across all gauges would show the same runout for a given cartridge. That's not possible now with all sorts of runout gauge and use designs.

Am I the only one who understands this deliema? I hope not...

 

[JFrank]

Well Fellas
I have it on fairly good authority that I’m a dumb ass among other things.....
However I can understand what Bart B. is describing and on the flip side life is much less complicated since I quit worrying about consentricity.
But maybe I don’t get IT.......

 

[mikecr]

Instead of breaking out little sections, and dismissing what we think doesn't matter, we can just make straight ammo. That is, straight any & every way you could possibly measure.
This is not that difficult.

 

[dmoran]

A problem with @Bart B.'s deliema (dilemma) is he assumes all ammo centers in the chamber shoulder before the round fires, from ejector or firing pin force. And many people understand that his assumption is not a fact. In many scenario's the ammo is centered off the bullet (such as jam seating), in which it is impossible that the case contacts the chamber or is centered by the case shoulder before the round fires. For an example, the jam-method of fire-forming of a 6Dasher, where not only would the case have to be shoved off the extractor, but also the bullet would have to get seated an additional .100" by the firing-pin strike and before the round fired, if his assumption was to be true.

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[garandman]

A problem with @Bart B.'s deliema (dilemma) is he assumes all ammo centers in the chamber shoulder before the round fires, from ejector or firing pin force. And many people understand that his assumption is not a fact. In many scenario's the ammo is centered off the bullet (such as jam seating), in which it is impossible that the case contacts the chamber or is centered by the case before the round fires. For an example, the jam-method of fire-forming of a 6Dasher, where not only would the case have to be shoved off the extractor, but also the bullet would have to get seated an additional .100" also, by the firing-pin strike and before the round fired, if his assumption was to be true.

His whole dilemma to what is wrong with concentric stands, all rest on his assumption being right to all scenario's, cases, and in all rifle types.

That whole "here's what I think I've experience and I insist its univerally true for everyone" thing.... there are darned few universals in the shooting world.

Even individual bullets in the SAME BOX will have differring ballistic coefficients, and machining tolerances.

 

[rwj]

Has anyone ever performed a Gauge R & R evaluation that they are willing to share on any of the concentricity devices currently for sale? The system’s capability will be higher than the gauge’s resolution... it wouldn’t be surprising for it to be much higher.