Loaded round vs. neck diameter measurements

[nmkid]

Quick question...How much smaller should the measurement of a loaded round, (at the neck) be then the neck chamber diameter? .002-.003-.004??

 

[CJ6]

I don't think there is a "perfect" measurement. The PPC is at .002, the 6-284 is at .0025, the 6.5 IHMSA is .004 as is the 308. Those are just some of the fitted neck sizes that I have.

 

[butchlambert]

What barrel and what use is it for? Don't get too tight and I've found that the old tight neck doesn't do much. Worry about your sizing, loads, and practice.

I'm not saying to use .020 clearance either.

 

[Wirelessguy2005]

I like to keep my 20 caliber wildcats around .002 -.003 neck clearance

 

[butchlambert]

I like to keep my 20 caliber wildcats around .002 -.003 neck clearance

What is the reason for it?

 

[Wirelessguy2005]

Mainly because that is a number I have settled on, I believe it keeps brass working to a minimum. Others may have a different opinion.

What is the reason for it?

 

[butchlambert]

Mainly because that is a number I have settled on, I believe it keeps brass working to a minimum. Others may have a different opinion.

Just curious, so a neck with .004 clearance would shorten your brass life?

 

[Wirelessguy2005]

Maybe and maybe not, again as stated in my original post it's a number I have settled on personally.

Just curious, so a neck with .004 clearance would shorten your brass life?

 

[butchlambert]

Maybe and maybe not, again as stated in my original post it's a number I have settled on personally.

Thank you.

 

[nmkid]

What barrel and what use is it for? Don't get too tight and I've found that the old tight neck doesn't do much. Worry about your sizing, loads, and practice.

I'm not saying to use .020 clearance either.

New Pac Nor barrel .270 neck for a 6-284. This rifle will be used for shooting at shiny rocks on hillsides and coyotes. Nothing serious, just for having fun.

 

[CJ6]

New Pac Nor barrel .270 neck for a 6-284. This rifle will be used for shooting at shiny rocks on hillsides and coyotes. Nothing serious, just for having fun.

So what ya thinking.. .266-.268 loaded ?

 

[InTheTenRing]

The norm use to be .002. It's been changed and many now say .001. If it's a for fun gun like u say I would go with .001. But if you want the most out of your gun you buy several bushings in different sizes and find which one gives u the best groups. Just like figuring out your jump to lands measurement.

 

[mikecr]

The norm use to be .002. It's been changed and many now say .001. If it's a for fun gun like u say I would go with .001. But if you want the most out of your gun you buy several bushings in different sizes and find which one gives u the best groups. Just like figuring out your jump to lands measurement.

This thread isn't about sizing amount, but of neck clearance amount.

 

[Alex Wheeler]

No less than .002" on a 6mm

 

[eric n]

No less than .002" on a 6mm

Outside of getting any junk in your chamber, is there any detrimental affects on accuracy by running it tighter?

 

[Alex Wheeler]

Outside of getting any junk in your chamber, is there any detrimental affects on accuracy by running it tighter?

Yes, the guns seem to get picky and want to throw fliers if you get a little too tight.

 

[butchlambert]

Kinda funny, nobody has posted why it needs to be .002 or there about. Why?

 

[mikecr]

Outside of getting any junk in your chamber, is there any detrimental affects on accuracy by running it tighter?

Depends on your runout.
Where you're running crooked ammo, in less clearance, you establish random chambered tension points.
This, leading to notions that a 'rad turd in a violin case' works better.
Well, this does alleviate some issues(while causing as many others), but there is no technical basis I'm aware of for any high clearance -in itself -improving accuracy.

When someone suggests there is this or that minimum clearance, they never hold technical basis for it. The truth is that ANY will suffice. That is, with any clearance(neck & end) allowing bullet release, a neck will do so without issue.

 

[butchlambert]

Depends on your runout.
Where you're running crooked ammo, in less clearance, you establish random chambered tension points.
This, leading to notions that a 'rad turd in a violin case' works better.
Well, this does alleviate some issues(while causing as many others), but there is no technical basis I'm aware of for any high clearance -in itself -improving accuracy.

When someone suggests there is this or that minimum clearance, they never hold technical basis for it. The truth is that ANY will suffice. That is, with any clearance(neck & end) allowing bullet release, a neck will do so without issue.

Oh really!

 

['Freak]

Kinda funny, nobody has posted why it needs to be .002 or there about. Why?

Maybe to prevent a too much imperfect concentricity betwixt the case body (and shoulder) and the bullet’s bearing surface from causing a too closely fitted neck to contact the chamber’s neck wall and then put in a bind the bullet whose bearing surface is poked up into the throat area where there’s possibly, at best, less than a quarter thousandth’s clearance on any side ...?