Help neede 308 neck turning

[ANDY T]

Hi help urgently needed

I have just go a new 308w barrel and it has a ,336mm chambered neck.
What would you recommend i turn the new cases walls down to.

What size bushing would you recommend to use with newly turned brass.

Also should i always stay with that bush or go smaller as the brass get used.

For got to say will be using Lapua brass

Please could you please give me some actual measurements on the above question and not give me am expatiation that will
only confuse me.

Thanks
Andy

 

[Yellow11]

,336mm chambered neck

Are you sure about that... perhaps you meant .336"?

If your chamber neck is .336", assume "say" 3 thou" clearance on loaded round i.e. loaded round's neck is .333". Deduct .308" (for bullet), which leave you 25thou" for the brass i.e. 0.0125" for your turned wall thickness.

... and for you sizing bush, try 2 thou under the loaded round size, viz, .331!

 

[Steve Blair]

Yellow11's advice is good. I have two .308 reamers. One, with .337" neck, is intended for unturned Winchester brass. The other, .342" neck, is for unturned Lapua brass. Both allow about .003-.004" loaded round clearance. When you turn the Lapua necks, don't be concerned if .0125" wall does not eliminate every thin spot. You will have eliminated the majority and made the neck more uniform. I turn Winchester necks with a .0125" setting to eliminate an annoying case mouth ridge. The cutter will occasionally touch a couple places elsewhere on the neck but is really intended to remove the ridge.

 

[338Lapua]

Are u turning necks for a tight neck 308 or just for 75% clean up.