Just ordered new barrel .308. .340 neck question

[fm1947]

Mr ten x .003 seems like a good number that's what I have on my 30BR

 

[Quickoz]

I run a .343 Nk in the chamber. My Lapua Palma brass give me around 338 loaded round . I don't like tight Nk chambers after my 6x47L barrel which was originally .266 and I've opened it to .275 for no turn brass.

My next 308 chamber will be 343 again. I think having that 4-5 thou clearence.

 

[jscandale]

So, you are able to measure to 5 decimal places for neck clearance on a piece of brass? Pretty spiffy.
Who makes a tape measure that small??

JS

 

[fm1947]

5 decimals, Yes, My Mitutoyo measures .00005 I actually got it in a pawn shop $15 many years ago, it is right on.

Quickoz , I will start with .003, and if need be I can turn them.

 

[jsthntn247]

With Norma brass in my 300 WM I can run 79gr of h1000 and the 210 bergers with no pressure signs. I got pressure at 77.5 with win brass and 75 with RWS. Must be pretty tough stuff.

 

[Mr. Ten-X]

Am at .0141" +/- .0001 neck thickness on the .340NK. 3-shot groups run in the 0's to 3's at 100 and had a 5-shot at 1K that measured 3.5"T x 5"W from the bipod.

 

[fm1947]

Nice

 

[jscandale]

Am I to understand that you are crediting such a outstanding group on .0001"??? Really???

JS

 

[fm1947]

js

What are you talking about .0001

 

[jscandale]

js

What are you talking about .0001

Exactly my point.

JS

 

[Mr. Ten-X]

+/- .0001 is the tolerance that I turn my necks to. It would likely shoot as well with a larger tolerance, but I can get it with little effort, so why not?

In the context of this conversation, the point is that the loaded ammo has .004" clearance and it shoots better than I can hold it.

I must learn how to block people....

 

[fm1947]

TenX I understood what you were talking about .0001 on the neck, I must be missing something on JS

 

[jscandale]

My point is that if you give a tenth mic to ten different guys, you'll get ten different measurements. Half the guys on this board claim to do all kinds of operations to "within a tenth". Hell, some guys talk about holding tolerances on a work piece that they can't even quantify, like 5 or 6 decimal places using equipment that costs less than a house.
When you've actually worked in an industry with equipment where a tenth can actually be held, this kind of talk is just forum fodder. I just find it kind of comical especially when talking about a piece of soft tubular brass that constantly flexes, expands and contracts with firing. I guess no one has every heard of tool deflection or work piece crush. Funny stuff...funny stuff, and I don't even have to pay admission to read.

JS

 

[fm1947]

got it

 

[jsthntn247]

I shot my .308 win .339 nk chamber yesterday. My brass was turned to .3355 loaded diameter (.0137 per side) and I had no problems what so ever with chambering rounds or loads getting hot before they should. Hope that helps.

 

[jonbearman]

Then dont read it if you dont have good imfo to help the poster.Personally I run .0035 to .004 on everything and even more on hunting guns.

 

[fm1947]

Thanks, Great, jsthntn247