Neck wall thickness after neck turning

[oldgunny]

I am neck turning .308 Win brass, but have no idea what the minimum safe thickness of the neck wall should be. Is there a standard. This will be used in a min-spec chamber. Thanks.

 

[amlevin]

I don't know about "Min Spec" but all my .308 win brass gets turned to .012" which seems to be the "number" that gives me a neck that is even for all the brass. That thickness setting on my turning tool cuts even the worst case at least 270 degrees of the circumference. Since I anneal frequently neck splitting hasn't been a problem and accuracy is great.

 

[artbosco]

I am neck turning .308 Win brass, but have no idea what the minimum safe thickness of the neck wall should be. Is there a standard. This will be used in a min-spec chamber. Thanks.

You don't need to know what the case neck wall thickness is.

Turn until a seated bullet in a case has an outside diameter in a dummy round that gives you .002" to .003" total clearance [.001" to .0015" on each side] in the chamber.

What's the neck chamber diameter that your reamer turned to? That's your starting point.

For example, I have a .330" neck in my 30BR. I turn so the OD with a seated bullet measures .328". Some look for an OD of .327".

 

[amlevin]

I am neck turning .308 Win brass, but have no idea what the minimum safe thickness of the neck wall should be. Is there a standard. This will be used in a min-spec chamber. Thanks.

You don't need to know what the case neck wall thickness is.

Turn until a seated bullet in a case has an outside diameter in a dummy round that gives you .002" to .003" total clearance [.001" to .0015" on each side] in the chamber.

What's the neck chamber diameter that your reamer turned to? That's your starting point.

For example, I have a .330" neck in my 30BR. I turn so the OD with a seated bullet measures .328". Some look for an OD of .327".

That makes sense if you have a custom chamber. What about those who shoot rifles with SAAMI spec'd chambers but want to make the necks uniform in thickness?

 

[gtl1946]

I would just skim cut which is cleaning up the neck 70-80% on a SAMI factory chamber .

 

[lal357]

I would just skim cut which is cleaning up the neck 70-80% on a SAMI factory chamber .

+1
i clean mine up my lapua lg primer pocket turned out to .0125 i also turned the lc brass i use for my 6.5CM to the same bullet run out is better also

 

[oldgunny]

Thanks for the anwsers, I guess the starting point will be to call the gunsmith and find out the neck diameter of the reamer.
Thanks again.

 

[Lapua40X]

I make a "skim" cut on my new brass to make certain the wall thickness is as consistent as possible. It often takes more cutting than one might expect. From there I do my final turning to accommodate the neck tension I'm looking for.

 

[amlevin]

Thanks for the anwsers, I guess the starting point will be to call the gunsmith and find out the neck diameter of the reamer.
Thanks again.

Why not just cast the chamber with Cerrosafe (Woods Metal). That way you are absolutely certain what your measurements are rather than getting an answer from your 'smith like "Let's see, I think I used that XXX #xxxx reamer on that rifle" (which I did once). You'd be amazed what you can learn from a chamber cast and if you follow the instructions to the letter the readings are exact.

 

[Joe R]

I turn the necks on my .308. When I first started doing on Federal brass, I was just shaving the high spots to a .016 thickness, that improved things a bit but concentricity was inconsistent . Then I decided to shave it to a uniform .014 and that made things a whole lot better and way more consistent. At the time I was shooting a Savage, now I just upgraded to a custom .308 with a standard SAAMI chamber and that seems to work well for this rifle also.
Joe