DARKKER:

"As originally spec'd, C260 was a certain mix, with a tensile strength spec'd at 70-75,000psi. ..... If someone else uses a different alloy, or tensile rating, it may not translate as well as hoped."


I analyzed some cases for my brother a few months ago, I thought Lapua was in here, it's not, but for what the info is worth here it is, I hope it contributes to the thread. This data is listed as MFG and Caliber, I do not know if the recipe translates across all calibers for a given MFG. This data is for a specific case, for a specific caliber, from a specific MFG.

Industry Brass 260 aka “Cartridge Brass”
Comments: Cartridge Brass
Copper, Cu 68.5 - 71.5 %
Zinc, Zn 28.5 - 31.5 %
Iron, Fe <= 0.050 %
Lead, Pb <= 0.070 %
Other, total <= 0.15 %

Federal 6.5 Creedmor
Comments: Brass 260
Copper 70.03%
Zinc 29.81%
Manganese .01%
Iron .05%
Tin .01%

Remington 280 Remington
Comments: Brass 260
Copper 71.55%
Zinc 28.25%
Aluminum .12%
Phosphorous .01%
Iron .04%
Tin .03%

Winchester .243 Win
Comments: Brass 260
Copper 69.99%
Zinc 29.52%
Aluminum .29%
Iron .06%
Nickle .03%
Tin .11%


Starline 7MM-08
Comments: 443
Copper 73.67%
Zinc 26.23%
Tin .04%
Iron .04%
Manganese .01%
Phosphorous .01%