SmallCaliberCentral

Any one know what it is?

I haven't seen it on any of the popular drawings (wiki, 6mmbr.com, etc.).

Some of my (individual) brass ranges .009" - .013".

It varys by manufacturer. I've seen Hornet cases as thin as .008", and larger hunting calibers as much as .020". All the .223 case family of cartridges run in the area you've already measured. I've never seen factory specs for brass case thickness either, and I've got a 1,000 page book of cartridge drawings here.

'funny that such a thing should be so elusive...

Just measured some from a batch of new Winchester brass. Readings were from +/- .01035 to +/- .01080

Wow, that looks really tight (low variance). Do you mean .008" - .0135" maybe?

Most likely...that would be the thickest brass this side of .50BMG or Naval 20mm cannon!

First reading were correct... Readings were from +/- .01035 to +/- .01080 several ran into the .01125 range.

MY tubing micrometer reads to 5 decimal places 0.00000

For comparison, new Lapua 6mmBR brass measures from .01270 to .01340

Micrometer picture w/ brass..........

Cover, are you saying any single case varies less than .00045" as you measure at a variety of points arond the neck of that single case, or do you mean that as you measure several cases at a single pint per case, that the variation case-to-case is less than 0.00045"?

Yes, on average any single case measures +/- .00045. I rotate the brass and take measurements about every 90* I wasn't going to measure all the new brass I had after your first question, but I did measure 12-15 cases for you and most fell within this spec.

The Lapua brass had a wider range for the starting avg. measurement but the variable per case was much smaller then the Winchester.

Wow, thanks for the data Cover. That's pretty darn impressive, especially for the price!!